Armies in the American Civil War

This article is designed to give background into the organization and tactics of Civil War armies. This brief survey is by no means exhaustive, but it should give enough material to have a better understanding of the capabilities of the forces that fought the American Civil War. Understanding these capabilities should give insight into the reasoning behind the decisions made by commanders on both sides.

The US Army in 1861
The Regular Army of the United States on the eve of the Civil War was essentially a frontier constabulary whose 16,000 officers and men were organized into 198 companies scattered across the nation at 79 different posts. In 1861, this Army was under the command of Brevet Lieutenant General Winfield Scott, the 75‑year‑old hero of the Mexican‑American War. His position as general in chief was traditional, not statutory, because secretaries of war since 1821 had designated a general to be in charge of the field forces without formal congressional approval. During the course of the war, Lincoln would appoint other generals with little success until finally appointing Lieutenant General Ulysses S. Grant to the position prior to the Overland Campaign. The field forces were controlled through a series of geographic departments whose commanders reported directly to the general in chief. This department system, frequently modified, would be used by both sides throughout the Civil War for administering regions under Army control. Army administration was handled by a system of bureaus whose senior officers were, by 1860, in the twilight of long careers in their technical fields. Six of the 10 bureau chiefs were over 70 years old. These bureaus, modeled after the British system, answered directly to the War Department and were not subject to the orders of the general in chief. The bureaus reflected many of today's combat support and combat service support branches; however, there was no operational planning or intelligence staff. American commanders before the Civil War had never required such a structure. This system provided suitable civilian control and administrative support to the small field army prior to 1861. Ultimately, the bureau system would respond sufficiently, if not always efficiently, to the mass mobilization required over the next four years. Indeed, it would remain essentially intact until the early 20th century. The Confederate government, forced to create an army and support organization from scratch, established a parallel structure to that of the US Army. In fact, many important figures in Confederate bureaus had served in the prewar Federal bureaus.

Raising armies
With the outbreak of war in April 1861, both sides faced the monumental task of organizing and equipping armies that far exceeded the prewar structure in size and complexity. The Federals maintained control of the Regular Army, and the Confederates initially created a Regular force, though in reality it was mostly on paper. Almost immediately, the North lost many of its officers to the South, including some of exceptional quality. Of 1,108 Regular Army officers serving as of 1 January 1861, 270 ultimately resigned to join the South. Only a few hundred of 15,135 enlisted men, however, left the ranks.

The federal government had two basic options for the use of the Regular Army. The government could divide the Regulars into training and leadership cadre for newly formed volunteer regiments or retain them in “pure” units to provide a reliable nucleus for the Federal Army in coming battles.

For the most part, the government opted to keep the Regulars together. During the course of the war, battle losses and disease thinned the ranks of Regulars, and officials could never recruit sufficient replacements in the face of stiff competition from the states that were forming volunteer regiments. By November 1864, many Regular units had been so depleted that they were withdrawn from front-line service, although some Regular regiments fought with the Army of the Potomac in the Overland Campaign. In any case, the war was fought primarily with volunteer officers and men, the vast majority of whom started the war with no previous military training or experience. However, by 1864, both the Army of the Potomac and the Army of Northern Virginia were largely experienced forces that made up for a lack of formal training with three years of hard combat experience. Neither side had difficulty in recruiting the numbers initially required to fill the expanding ranks. In April 1861, President Abraham Lincoln called for 75,000 men from the states’ militias for a three‑month period.

This figure probably represented Lincoln's informed guess as to how many troops would be needed to quell the rebellion quickly. Almost 92,000 men responded, as the states recruited their “organized” but untrained militia companies. At the First Battle of Bull Run in July 1861, these ill‑trained and poorly equipped soldiers generally fought much better than they were led. Later, as the war began to require more manpower, the federal government set enlistment quotas through various “calls,” which local districts struggled to fill. Similarly, the Confederate Congress authorized the acceptance of 100,000 one‑year volunteers in March 1861. One‑third of these men were under arms within a month. The Southern spirit of voluntarism was so strong that possibly twice that number could have been enlisted, but sufficient arms and equipment were not then available.

As the war continued and casualty lists grew, the glory of volunteering faded, and both sides ultimately resorted to conscription to help fill the ranks. The Confederates enacted the first conscription law in American history in April 1862, followed by the federal government's own law in March 1863. Throughout these first experiments in American conscription, both sides administered the programs in less than a fair and efficient way. Conscription laws tended to exempt wealthier citizens, and initially, draftees could hire substitutes or pay commutation fees. As a result, the average conscript maintained poor health, capability, and morale. Many eligible men, particularly in the South, enlisted to avoid the onus of being considered a conscript. Still, conscription or the threat of conscription ultimately helped provide a large number of soldiers.

Conscription was never a popular program, and the North, in particular, tried several approaches to limit conscription requirements. These efforts included offering lucrative bounties, fees paid to induce volunteers to fill required quotas. In addition, the Federals offered a series of reenlistment bonuses, including money, 30‑day furloughs, and the opportunity for veteran regiments to maintain their colors and be designated as “veteran” volunteer infantry regiments. The Federals also created an Invalid Corps (later renamed the Veteran Reserve Corps) of men unfit for front‑line service who performed essential rear area duties. In addition, the Union recruited almost 179,000 African-Americans, mostly in federally organized volunteer regiments. In the South, recruiting or conscripting slaves was so politically sensitive that it was not attempted until March 1865, far too late to influence the war.

Whatever the faults of the manpower mobilization, it was an impressive achievement, particularly as a first effort on that scale. Various enlistment figures exist, but the best estimates are that approximately two million men enlisted in the Federal Army from 1861 to 1865. Of that number, one million were under arms at the end of the war. Because the Confederate records are incomplete or lost, estimates of their enlistments vary from 600,000 to over 1.5 million. Most likely, between 750,000 and 800,000 men served the Confederacy during the war, with peak strength never exceeding 460,000 men.

The unit structure into which the expanding armies were organized was generally the same for Federals and Confederates, reflecting the common roots of both armies. The Federals began the war with a Regular Army organized into an essentially Napoleonic, musket-equipped structure. Both sides used a variant of the old Regular Army structure for newly formed volunteer regiments. The Federal War Department established a volunteer infantry regimental organization with a strength that could range from 866 to 1,046 (varying in authorized strength by up to 180 infantry privates). The Confederate Congress field its 10‑company infantry regiment at 1,045 men. Combat strength in battle, however, was always much lower (especially by the time of the Overland Campaign) because of casualties, sickness, leaves, details, desertions, and straggling.

The battery remained the basic artillery unit, although battalion and larger formal groupings of artillery emerged later in the war in the eastern theater. Four under strength Regular artillery regiments existed in the US Army at the start of the war and one Regular regiment was added in 1861, for a total of 60 batteries. Nevertheless, most batteries were volunteer organizations. For the first years of the war and part way into the Overland Campaign, a Federal battery usually consisted of six guns and had an authorized strength of 80 to 156 men. A battery of six 12‑pound Napoleons could include 130 horses. If organized as “horse” or fling artillery, cannoneers were provided individual mounts, and more horses than men could be assigned to the battery. After the battle of Spotsylvania in 1864, most of the Army of the Potomac's artillery was reorganized into four-gun batteries. Their Confederate counterparts, plagued by limited ordnance and available manpower, usually operated throughout the war with a four-gun battery, often with guns of mixed types and calibers. Confederate batteries seldom reached their initially authorized manning level of 80 soldiers.

Prewar Federal mounted units were organized into five Regular regiments (two dragoon, two cavalry, and one mounted rifle), and one Regular cavalry regiment was added in May 1861. Although the term “troop” was officially introduced in 1862, most cavalrymen continued to use the more familiar term “company” to describe their units throughout the war. The Federals grouped two companies or troops into squadrons, with four to six squadrons comprising a regiment. Confederate cavalry units, organized in the prewar model, were authorized 10 76-man companies per regiment. Some volunteer cavalry units on both sides also formed into smaller cavalry battalions. Later in the war, both sides began to merge their cavalry regiments and brigades into division and corps organizations.

For both sides, the infantry unit structure above regimental level was similar to today's structure, with a brigade controlling three to five regiments and a division controlling two or more brigades. Federal brigades generally contained regiments from more than one state, while Confederate brigades often consisted of regiments from the same state. In the Confederate Army, a brigadier general usually commanded a brigade, and a major general commanded a division. The Federal Army, with no rank higher than major general until 1864, often had colonels commanding brigades, brigadier generals commanding divisions, and major generals commanding corps and armies. Grant received the revived rank of lieutenant general in 1864, placing him with clear authority over all of the Federal armies, but rank squabbles between the major generals appeared within the Union command structure throughout the Overland Campaign.

The large numbers of organizations formed are a reflection of the politics of the time. The War Department in 1861 considered making recruitment a Federal responsibility, but this proposal seemed to be an unnecessary expense for the short war initially envisioned. Therefore, the responsibility for recruiting remained with the states, and on both sides state governors continually encouraged local constituents to form new volunteer regiments. This practice served to strengthen support for local, state, and national politicians and provided an opportunity for glory and high rank for ambitious men. Although such local recruiting created regiments with strong bonds among the men, it also hindered filing the ranks of existing regiments with new replacements. As the war progressed, the Confederates attempted to funnel replacements into units from their same state or region, but the Federals continued to create new regiments. Existing Federal regiments detailed men back home to recruit replacements, but these efforts could never successfully compete for men joining new local regiments. The newly formed regiments thus had no seasoned veterans to train the recruits, and the battle-tested regiments lost men faster than they could recruit replacements. Many regiments on both sides (particularly for the North) were reduced to combat ineffectiveness as the war progressed. Seasoned regiments were often disbanded or consolidated, usually against the wishes of the men assigned.

The infantry regiment was the basic administrative and tactical unit of the Civil War armies. Regimental headquarters consisted of a colonel, lieutenant colonel, major, adjutant, quartermaster, surgeon (with rank of major), two assistant surgeons, a chaplain, sergeant major, quartermaster sergeant, commissary sergeant, hospital steward, and two principal musicians. Each company was staffed by a captain, a first lieutenant, a second lieutenant, a first sergeant, four sergeants, eight corporals, two musicians, and one wagoner. The authorized strength of a Civil War infantry regiment was about 1,000 officers and men, arranged in ten companies plus a headquarters and (for the first half of the war at least) a band. Discharges for physical disability, disease, special assignments (bakers, hospital nurses, or wagoners), court-martial, and battle injuries all combined to reduce effective combat strength. Before too long a typical regiment might be reduced to less than 500. Brigades were made up of two or more regiments, with four regiments being most common. Union brigades averaged 1,000 to 1,500 men, while on the Confederate side they averaged 1,500 to 1,800. Union brigades were designated by a number within their division, and each Confederate brigade was designated by the name of its current or former commander.

Divisions were formed of two or more brigades. Union divisions contained 1,500 to 4,000 men, while the Confederate division was somewhat larger, containing 5,000 to 6,000 men. As with brigades, Union divisions were designated by a number in the Corps, while each Confederate division took the name of its current or former commander. Corps were formed of two or more divisions. The strength of a Union corps averaged 9,000 to 12,000 officers and men, those of Confederate armies might average 20,000. Two or more corps usually constituted an army, the largest operational organization. During the Civil War there were at least 16 armies on the Union side, and 23 on the Confederate side. In the Eastern Theater, the two principal adversaries were the Union Army of the Potomac and the Confederate Army of Northern Virginia. There were generally seven corps in the Union Army of the Potomac, although by the spring of 1864 the number was reduced to four. From the Peninsula campaign through the Battle of Antietam the Confederate Army of Northern Virginia was organized into Longstreet's and Jackson's "commands," of about 20,000 men each. In November 1862 the Confederate Congress officially designated these commands as corps. After Jackson's death in May 1863 his corps was divided in two, and thereafter the Army of Northern Virginia consisted of three corps.



Leaders
Because the organization, equipment, tactics, and training of the Confederate and Federal armies were similar, the performance of units in battle often depended on the quality and performance of their individual leaders. Both sides sought ways to find this leadership for their armies. The respective central governments appointed the general officers. At the start of the war, most, but certainly not all, of the more senior officers had West Point or other military school experience. In 1861, Lincoln appointed 126 general officers, of which 82 were or had been professionally trained officers. Jefferson Davis appointed 89, of which 44 had received professional training. The rest were political appointees, but of these only 16 Federal and 7 Confederate generals lacked military experience.

Of the lower ranking volunteer officers who comprised the bulk of the leadership for both armies, state governors normally appointed colonels (regimental commanders). States also appointed other field grade officers, although many were initially elected within their units. Company grade officers were usually elected by their men. This long‑established militia tradition, which seldom made military leadership and capability a primary consideration, was largely an extension of states’ rights and sustained political patronage in both the Union and the Confederacy.

Much has been made of the West Point backgrounds of the men who ultimately dominated the senior leadership positions of both armies, but the graduates of military colleges were not prepared by such institutions to command divisions, corps, or armies. Moreover, though many leaders had some combat experience from the Mexican War era, very few had experience above the company or battery level in the peacetime years prior to 1861. As a result, the war was not initially conducted at any level by “professional officers” in today's terminology. Leaders became more professional through experience and at the cost of thousands of lives. General William T. Sherman would later note that the war did not enter its “professional stage” until 1863. By the time of the Overland Campaign, many officers, though varying in skill, were at least comfortable at commanding their formations.

Civil War Staffs
In the Civil War, as today, the success of large military organizations and their commanders often depended on the effectiveness of the commanders’ staffs. Modern staff procedures have evolved only gradually with the increasing complexity of military operations. This evolution was far from complete in 1861, and throughout the war, commanders personally handled many vital staff functions, most notably operations and intelligence. The nature of American warfare up to the mid-19th century did not seem to overwhelm the capabilities of single commanders. However, as the Civil War progressed the armies grew larger and the war effort became a more complex undertaking and demanded larger staffs. Both sides only partially adjusted to the new demands, and bad staff work hindered operations for both the Union and Confederate forces in the Overland Campaign.

Civil War staffs were divided into a “general staff” and a “staff corps.” This terminology, defined by Winfield Scott in 1855, differs from modern definitions of the terms. Except for the chief of staff and aides-de-camp, who were considered personal staff and would often depart when a commander was reassigned, staffs mainly contained representatives of the various bureaus, with logistical areas being best represented. Later in the war, some truly effective staffs began to emerge, but this was the result of the increased experience of the officers serving in those positions rather than a comprehensive development of standard staff procedures or guidelines.

Major General George B. McClellan, when he appointed his father‑in‑law, was  the  first  to  officially  use  the  title  “chief  of staff.” Even though many senior commanders had a chief of staff, this position was not used in any uniform way and seldom did the man in this role achieve the central coordinating authority of the chief of staff in a modern headquarters. This position, along with most other staff positions, was used as an individual commander saw fit, making staff responsibilities somewhat different under each commander. This inadequate use of the chief of staff was among the most important shortcomings of staffs during the Civil War. An equally important weakness was the lack of any formal operations or intelligence staff. Liaison procedures were also ill-defined, and various staff officers or soldiers performed this function with little formal guidance. Miscommunication or lack of knowledge of friendly units proved disastrous time after time in the war's campaigns.

Armies at Vicksburg
Major General Ulysses S. Grant's Army of the Tennessee was organized into four infantry corps. Major General Stephen A. Hurlbut's XVI Corps, however, remained headquartered in Memphis performing rear-area missions throughout the campaign, although nearly two divisions did join Grant during the siege. The remaining three corps, containing ten divisions with over 44,000 effectives, composed Grant's maneuver force during the campaign. Although some recently recruited "green" regiments participated, the bulk of Grant's army consisted of veteran units, many of which had fought with distinction at Forts Henry and Donelson, Shiloh, and Chickasaw Bayou. Of Grant's senior subordinates, the XV Corps commander, Major General William T. Sherman, was his most trusted. Ultimately to prove an exceptional operational commander, Sherman was an adequate tactician with considerable wartime command experience. He and Major General James B. McPherson, commander of XVII Corps, were West Pointers. McPherson was young and inexperienced, but both Grant and Sherman felt he held great promise. Grant's other corps commander, Major General John A. McClernand, was a prewar Democratic congressman who had raised much of his XIII Corps specifically so that he could command an independent Vicksburg expedition. A self-serving and politically ambitious man who neither enjoyed nor curried Grant's favor, he nonetheless was an able organizer and tactical commander who had served bravely at Shiloh. The division commanders were a mix of trained regular officers and volunteers who formed a better-than-average set of Civil War commanders.

Lieutenant General John C. Pemberton, a Pennsylvania-born West Pointer who had served with Jefferson Davis in the Mexican War, resigned his federal commission to join the South at the start of the war. Pemberton's army in the Vicksburg campaign consisted of five infantry divisions with no intermediate corps headquarters. Counting two brigades that briefly joined Pemberton's command during the maneuver campaign, he had over 43,000 effectives, many of whom had only limited battle experience. Of Pemberton's subordinates, Brigadier General John S. Bowen, a West Point classmate of McPherson's, was an exceptionally able tactical commander. Major General Carter L. Stevenson was also West Point trained, and the other division commander in the maneuver force, Major General William W. Loring, was a prewar Regular colonel who had worked his way up through the ranks. Significantly, none of these three men had any real respect for their commander and would prove to be less than supportive of him. Pemberton's other division commanders, Major Generals Martin L. Smith and John H. Fomey, both West Pointers, would remain in or near the city, commanding Vicksburg's garrison troops throughout the campaign.

Although Pemberton's five divisions represented the main Confederate force in the Vicksburg campaign, his army came under the jurisdiction of a higher headquarters, General Joseph E. Johnston's Department of the West. Johnston, in 1861, had been the Quartermaster General of the Regular Army and one of only five serving general officers. He had commanded in the eastern theater early in the war until severely wounded. In November 1862 after several months of convalescence, he assumed departmental command in the west. Johnston assumed direct command in Mississippi on 13 May 1863 but was unable to establish effective control over Pemberton's forces. When Pemberton became besieged in Vicksburg, Johnston assembled an Army of Relief but never seriously threatened Grant.

Morale of the troops was a serious concern for both the Union and Confederate commanders. Grant's army suffered terribly from illness in the early months of the campaign, which it spent floundering in the Louisiana swamps. But the men recovered quickly once they gained the high ground across the river. Inured to hardship, these men were served by able commanders and hardworking staffs. Once movements started, morale remained high, despite shortfalls in logistical support. Pemberton's men, although not always well served by their commanders, fought hard for their home region through the battle of Champion Hill. Although they briefly lost their resolve after that defeat, once behind the formidable works at Vicksburg, they regained a level of morale and effectiveness that only began to erode weeks later when they were faced with ever-increasing Federal strength and their own supply shortages.

Armies in the Overland Campaign
The forces in the Overland Campaign evolved through several organizational changes over the course of the two-month struggle. The details of these changes are covered in the campaign overview and in the appendixes. Some key aspects of these organizations are summarized below.

On the Union side, Lieutenant General Ulysses S. Grant, in addition to being the commander of all of the Union forces arrayed against the Confederacy, commanded all Union forces in the eastern theater of operations that fought in the Overland Campaign. His main force was Major General George G. Meade's Army of the Potomac, which initially consisted of three infantry corps and one cavalry corps. An additional infantry corps, the IX Corps under Major General Ambrose E. Burnside, began the campaign as a separate corps reporting directly to Grant, but was later assigned to the Army of the Potomac. Major General Franz Sigel commanded a Union army in the Shenandoah Valley that had only an indirect role in the Overland Campaign. On the other hand, Major General Benjamin F. Butler's Army of the James was more directly involved in the campaign. His army consisted of two infantry corps and about a division's worth of cavalry troops. Later in the campaign, at Cold Harbor, one of Butler's corps, the XVIII under Major General William F. Smith, was temporarily attached to the Army of the Potomac. The initial strength of the Army of the Potomac and the IX Corps at the beginning of the Overland Campaign was slightly under 120,000 men.

There are some factors affecting the strength, quality, and organization of the Union forces that should be noted. First, just prior to the campaign, the Army of the Potomac had abolished two of its infantry corps (the I and III Corps, both of which had been decimated at Gettysburg) and consolidated their subordinate units into the remaining three corps (II, V, and VI). This definitely streamlined the Army's command and control, but it also meant that some divisions and brigades were not accustomed to their new corps’ methods and procedures at the start of the campaign. Second, soldiers in a large number of the Federal regiments were approaching the expiration dates of their enlistments just as the campaign was set to begin in May 1864. Most of the troops in these regiments had enlisted for three years in 1861, and they represented the most experienced fighters in the Army. A surprisingly large number of these soldiers reenlisted (over 50 percent), but there was still a large turnover and much disruption as many of the regiments that reenlisted returned to their home states for furloughs and to recruit replacements. Finally, the Union did tap a new source for soldiers in 1864: the “heavy artillery” regiments. These were units designed to man the heavy artillery in the fortifications around Washington, DC. Grant decided to strip many of these regiments from the forts and use them as infantry in the 1864 campaign, and he employed these forces more extensively as his losses accumulated. The heavy artillery regiments had a slightly different structure than the traditional infantry regiments, and they had not suffered battle casualties; thus, they often still possessed about 1,200 soldiers in a regiment. This was as large as a veteran Union brigade in 1864.

On the Confederate side, there was no overall commander in chief or even a theater commander with authority similar to that of Grant. Officially, only President Jefferson Davis had the authority to coordinate separate Confederate armies and military districts. However, the commander of the Army of Northern Virginia, General Robert E. Lee, had considerable influence over affairs in the entire eastern theater due to the immense respect he had earned from Davis and other Confederate leaders. Lee's army consisted of three infantry corps and a cavalry corps. One of these corps (Lieutenant General James Longstreet's I Corps) had been on detached duty just prior to the opening of the campaign and would not join the rest of Lee's army until the second day of the battle of the Wilderness

(6 June). Additional Confederate forces in the theater included Major General John C. Breckinridge's small army in the Shenandoah Valley and General P.G.T. Beauregard's forces protecting Richmond, southern Virginia, and northern North Carolina. In the course of the campaign, Lee received some reinforcements from both Breckinridge and Beauregard. The Army of Northern Virginia (including Longstreet's I Corps) began the campaign with about 64,000 soldiers. Although plagued by an overall shortage in numbers, Lee had fewer worries about the organization and quality of his manpower. Most of his soldiers had enlisted for the duration of the war, thus his army lost few regiments due to expired terms of service. Also, thanks to its better replacement system, Confederate regiments were usually closer to a consistent strength of 350 to 600 men instead of the wild disparity of their Union counterparts (as low as 150 soldiers in the decimated veteran regiments and as much as 1,200 in the heavy artillery regiments). Overall, Lee could count on the quality and consistency of his units, and he did not have to endure the turmoil of troop turnover and organizational changes that hindered Grant's forces.

As for staffs, on the Union side Grant maintained a surprisingly small staff for a commander in chief. His personal chief of staff was Major General John A. Rawlins, a capable officer who generally produced concise and well‑crafted orders. In addition, he was Grant's alter ego, a trusted friend who took it upon himself to keep Grant sober. In fact, recent scholarship indicates that Grant's drinking was far less of a problem than formerly indicated, and there were certainly no drinking difficulties during the Overland Campaign. The rest of Grant's small staff consisted of a coterie of friends who had earned Grant's trust from their common service in the western theater campaigns. In general, this staff performed well, although a few glaring mistakes would come back to haunt the Union effort. Of course, one of the major reasons Grant could afford to keep such a small staff in the field was that the chief of staff for the Union armies, Major General Henry W. Halleck, remained in Washington with a large staff that handled Grant's administrative duties as general in chief. In fact, Halleck was a superb staff officer who tactfully navigated the political seas of Washington and gave Grant the freedom to accompany the Army of the Potomac in the field.

In contrast to Grant's field staff, Meade had a huge staff that Grant once jokingly described as fitting for an Imperial Roman Emperor. Meade's chief of staff was Major General Andrew A. Humphreys, an extremely capable officer who only reluctantly agreed to leave field command to serve on the army's staff. Humphreys has received some criticism for not pushing the Army of the Potomac through the Wilderness on 4 May; but for most of the campaign, his orders were solid and his movement plan for the crossing of the James River was outstanding. Another excellent officer on the army staff was the chief of artillery, Major General Henry J. Hunt. Recognized as one of the war's foremost experts on artillery, Hunt had a more active role in operational matters than most artillery chiefs who usually just performed administrative duties. The rest of Meade's staff was of mixed quality. In addition, the poor caliber of Union maps coupled with some mediocre young officers who were used as guides repeatedly led to misdirected movements and lost time.

Compared to Meade's large headquarters, Lee maintained a smaller group of trusted subordinates for his staff. Lee did not have a chief of staff, thus much of the responsibility for writing his orders fell on the shoulders of a few personal aides and secretaries, especially Lieutenant Colonel Charles Marshall. Lee employed several young officers, such as Lieutenant Colonel Walter Taylor and Colonel Charles S. Venable, as aides, and had great faith in these men to transmit his orders to subordinates. However, the lack of a true staff to ease his workload probably took its toll on Lee who was ill and physically exhausted by the time of the North Anna battles at the end of May. Other than his young aides, Lee had several other staff officers of mixed quality. His chief of artillery, Brigadier General William N. Pendleton, was mediocre at best, and the Army commander usually relegated his chief of artillery to strictly administrative duties. On the other hand, Major General Martin Luther (M.L.) Smith, Lee's chief engineer, played an active and generally positive role throughout the campaign.

Weapons
There were a wide variety of weapons used during the Civil War, especially in the early days as both sides struggled to arm their rapidly-expanding forces. Everything from antique flintlock firearms to early examples of machine guns and sniper rifles saw use to one extent or the other. However, the most common weapon to be used by Northern and Southern soldiers was the rifled musket. Born from the development of the percussion cap and the Minié ball, rifled muskets had much greater range than smoothbore muskets while being easier to load than previous rifles.

Most firearms were muzzleloaders which were armed by pouring the gunpowder and bullet down the muzzle. While they only fired once before needing to be reloaded, a trained soldier could achieve a rate of fire of three rounds per minute. Newer breechloaders were easier and quicker to reload, but perhaps the most revolutionary development were repeating firearms, which could fire multiple times before reloading. However, for a number of reasons, repeating firearms did not see widespread use.

The diversity of long guns in the war led to a classification system which categorized them by their quality and effectiveness. There were "first class" weapons like Springfield rifles, "second class" weapons like the older M1841 Mississippi rifle, and "third class" weapons like the Springfield Model 1842 musket. Efforts were made to ensure that troops had the best possible firearms available, including rearming with captured enemy weapons after a battle.

Overview
The military tactics of the Confederate and Union armies were virtually identical during the Civil War, being derived from the same traditions which had originated in Europe. This type of warfare involved infantry marching shoulder-to-shoulder in lines, columns and other formations in order to deliver volley fire on the enemy before charging with bayonets. Such tactics were necessary in previous wars as the primary infantry weapon, the smoothbore musket, had an effective range of only 100 yards and was complex to reload. Cavalry and artillery played a supporting role to the infantry and used for both offensive and defensive roles. Cavalry were sent to scout for the enemy and protect the army's flanks and rear from attack, and during battle would charge into enemy infantry if they retreated or became disorganized. Artillery would blast holes in the enemy's lines to create gaps for the infantry or cavalry to exploit or to defend a position from the enemy's advance. These tactics were based on drill manuals, many derived from European manuals influenced by experience in the Napoleonic Wars, which formed the basis of individual and unit training. Many commanders had practical experience employing these tactics during the earlier Mexican-American War, but this experience was limited since the scale of fighting then was much smaller than the massive armies which eventually came to dominate the Civil War.

Before battle could begin the enemy had to be found first, a task most commonly carried out by the cavalry. They might also be located by setting up signal stations equipped with signal flags, sending out spies, interrogating prisoners of war, or reading the local newspaper. The Union took the novel approach of using hot air balloons to locate enemy troops during the early years of the war, but this was considered a cost-ineffective practice and later discontinued. With the enemy located, infantry formed up in their battle lines as artillery and skirmishers harassed the enemy with preparatory fire. A flanking maneuver was the preferred method of attack but not always possible, making it often necessary to conduct a frontal assault. In this case feints were made in the hope of drawing off the enemy's attention. Prior to the Civil War and in its first year the regiment was the primary unit of maneuver on the battlefield, but it was soon superseded by the brigade in both armies, often as part of a larger division-based attack. Two or more of a division's brigades would lead the attack with the rest as a ready reserve, and its movements were often part of a larger coordinated attack by a corps.

Once the order to attack was given, successive lines of infantry would advance on the enemy at a walking pace until the first line got to within 200 yards or less, whereupon (ideally) they fired a single volley at the enemy and charged with bayonets to overrun their position. If successful, the first line would regroup in place as the succeeding lines passed through to attack the next position; if they became bogged down or forced to retreat, the next line would pass through to continue the attack. Much more often though, the attackers stopped within 100 yards of the enemy and begin exchanging fire with them until using up their ammunition. At this point they would either be driven off or press onwards with their bayonets. In the smoke and confusion of battle, a regiment's colors was an important rally point to help soldiers identify where their unit was and which direction it was headed. The colors also represented the unit's fighting spirit, and the fiercest fighting often centered around trying to seize the enemy's flag or defending your own from capture.

When on the defensive, the main line would be formed around a strong terrain feature (stone wall, embankment, etc.) or fieldworks, either of which ideally allowed for flanking fire. Supporting lines were placed behind the main line, on a hill overlooking it if possible but otherwise providing a ready reserve. Counter-battery fire would attempt to knock out the enemy's artillery while skirmishers harassed the attacker as they advanced. Once within range, the defending infantry attempted to drive off the enemy with superior firepower or, if timed right, a counter-charge of their own. Fieldworks were used extensively during the Civil War. Even outside of sieges, both armies made every effort to construct whatever defensive fortifications that time permitted. Examples included rifle pits, abatises, wire obstacles, land mines, and palisades. Truly impressive trench systems were constructed, often thanks to the widespread use of Black laborers by both armies.

Cavalry were rarely used in actual battle in the first years of the war, instead more often being used for scouting and raiding missions. By the latter half of the war cavalry on both sides had developed battle tactics unique from their European counterparts. Instead of masses of heavy cavalry charging into infantry, a cavalry force would leave a portion of its troopers mounted while the rest dismounted to engage in a firefight. The widespread employment of repeating rifles gave Union cavalry a particular advantage in this phase as it allowed them to utilize an early form of marching fire. If the firefight did not achieve success, the dismounted portion could clear any obstacles to make way for a cavalry charge by the mounted troopers. Such charges were capable of overrunning even defensive fortifications, but if unsuccessful the entire force could remount and use their mobility to attack at a later time from another direction. In this way an enemy could be defeated in detail as these successive attacks forced them to spread out and allowed isolated elements to eventually be overwhelmed.

Analysis
The traditional interpretation of Civil War tactics is that they were horribly outdated in the face of new revolutionary technology, namely the widespread use of the rifled musket. Where before the smoothbore musket had an effective range of 100 yards and longer-ranged rifles were specialist weapons, now most soldiers had a weapon with an effective range of 500 yards. This meant more firepower could be directed onto the enemy from greater distances, giving the defender a significant advantage as they could more easily repel infantry and cavalry charges. Frontal attacks were reduced to bloody messes and cavalry were forced to fight like mounted infantry. Artillery as well was forced to operate further away from enemy infantry to avoid being picked off by their rifles, reducing the effect of their firepower as they could no longer use cannister shot offensively.

Many contemporaries did complain at what they saw as an inappropriate devotion to European tactical doctrine, citing it as being responsible for the terrible casualties suffered and a desire to develop more 'American' tactics. Such criticisms were picked up and continued by later historians such as James M. McPherson and Edward Hagerman, arguing that the rifle made the continued use of linear tactics obsolete and bloody. The ultimate result was that greater casualties were suffered, battles became less decisive, and trench warfare became more prevalent in the Civil war, presaging what was to come in World War I.

More recently, historians like Earl Hess and Allen Guelzo have challenged this interpretation, arguing the tactics used during the Civil War remained practical and were not rendered ineffective by the rifle musket. Hess cites independent studies of Civil War battle records by Paddy Griffith, Mark Grimsley and Brent Nosworthy which show that combat largely took place within or only slightly outside the effective range of smoothbore muskets, indicating no significant difference from previous wars. The reason for these continued short ranges were several: the use of black powder which fouled barrels and obscured the battlefield; a slower muzzle velocity for rifled muskets, resulting in a curved trajectory when attempting to hit targets further away; and a general lack of target practice on both sides of the conflict.

Paddy Griffith argues there is no evidence that the elaborate earthworks of the Civil War were any more necessary to deal with modern rifle weaponry than they had been in previous wars. Instead their increasing prevalence during the war was due to psychological reasons: a more risk-averse populace combined with officers influenced by the defensive-oriented teachings of West Point instructors like Dennis Hart Mahan. Stephen Starr could find no proof that cavalry in the Civil War made a conscious choice to change their tactics in response to the rifle and that they continued to fight both mounted and dismounted.

Logistics
Military logistics during the Civil War was greatly affected by the unprecedented size and scope of the conflict, as well as the widespread application of new technologies. Inventions such as canning and condensed milk promised to alleviate some of the issues faced by soldiers during long campaigns. Steam engines allowed for large numbers of men and materiel to be transported on a continental scale via steamship and railroad in a matter of days, while electrical telegraphy allowed for the coordination of these forces over the same vast distances.

Technologies like the steam engine and telegraphy, along with the ability to produce immense amounts of munitions and other warfighting material, were the direct result of the Industrial Revolution's transformative effect on the United States, particularly in the North where the majority of the nation's manufacturing capabilities were located. However, just as important as producing the arms and equipment was ensuring it got to the troops in a timely manner, requiring a level of leadership and administrative skill which had no precedent. Ultimately the North was successful in developing the infrastructure to arm, feed and clothe a million soldiers at once, and to maintain its armies across distances which had confounded Napoleon during his invasion of Russia.

Organization
Administration of the pre-war United States Army was handled by the staff bureaus of the Department of War. They were headquartered in Washington, D.C. and the heads of these bureaus reported directly to the Secretary of War. Each bureau or department acted independently of the other and set their own standards of operation. Of these, four were considered the "supply" departments responsible for the logistical support of the Army.

The Medical Department was responsible for acquiring and distributing medicine, medical equipment, hospital food and similar supplies. The Ordnance Department was responsible for the development, procurement, storage, distribution and repair of all ordnance and ordnance-related equipment such as limbers and caissons and accoutrements. The Subsistence Department was in charge of the purchase, storage and distribution of food rations and related items. And the Quartermaster Department was responsible for all other supplies not covered by another department like clothing, tents, horses and fodder. It was also responsible for any non-Ordnance vehicles (i.e. wagons, ambulances, traveling forges); constructing and maintaining Army buildings; and providing transportation services for the entire Army, including the other supply departments.

The Confederates adopted the same bureau system as the Federal government, including the four supply departments responsible for similar logistical functions. A fifth department, the Niter and Mining Bureau, was responsible for the raw materials necessary for producing ordnance. However, the bureaus suffered from a persistent shortage of experienced personnel during the war, while the political infighting and lack of coordination was even worse than in the Union Army. An inability to coordinate their efforts at all levels of administration only exacerbated the Confederates' precarious supply situation. The basic organizational unit was the geographic department, whose commander communicated directly with the bureaus for their needs, although as the war progressed some departments were combined together under a "division" headquarters. Department commanders had total control over logistical operations within their area of responsibility. Depots were set up in major urban centers from which supplies would be procured - mostly via low-bid contracts initiated by the depot commanders themselves - and made ready for distribution to units in the field. Additional advanced and temporary depots would be set up at cities or transportation hubs closer to the fighting as needed to support ongoing operations. Despite their importance though, until 1864 many of these depots were commanded by mere captains.

Starting at the regimental level, each military unit had a number of logistical staff officers responsible for keeping their units provisioned. Once supplies arrived at an advanced depot via rail or steamship, these officers were responsible for organizing wagon trains to pick them up and take them to the field units. A regiment's quartermaster, commissary, and ordnance officers were selected from among its lieutenants, while those of larger units were supposed to be provided by the supply departments themselves. However, chronic shortages often required for line officers to be assigned to these duties, or for staff officers to cover multiple roles at once.

Additionally, with the exception of a small number of trained NCOs and specialists, there were no enlisted personnel assigned to help carry out the routine logistical work. Either civilian contractors had to be hired, or soldiers had to be reassigned from their line units, to perform these necessary duties. Civilians were not as reliable as Army personnel, but reassigning soldiers diminished the fighting power of their units. One alternative utilized by the Union Army was hiring African-Americans, including so-called "contraband" or freed slaves. In a variety of roles, from teamsters to ambulance drivers to hostlers, Black workers proved to be more trustworthy and often performed better. The Confederates requisitioned slaves to perform the same work, but doing so was considered a burden to the slaveowners as it decreased economic activity.

Arms and Ammunition
There was a pressing need for weaponry at the start of the war as neither side had sufficient quantities of modern firearms to equip their growing armies. Eventually this problem was alleviated through a combination of production at government arsenals and contracting with both domestic and foreign manufacturers. In this respect the North was better able to equip its forces, being the site of most of the nation's arms manufacturers with 28 arsenals, foundries and armories. In total, the North was able to furnish over four million small arms and melee weapons, over one billion rounds of small arms ammunition, nearly eight thousand artillery pieces and more than eight million artillery rounds during the war. Still, the South was able to adequately meet its needs by building up its industrial capacity with 20 arsenals and factories, salvaging captured Federal weapons, and gunrunning through the Union blockade.

There was no "standard" in the amount of ammunition carried by soldiers, being dependent on factors like availability and commanders' orders. On average though, an infantryman would have 200 rounds of ammunition for his rifle: 60 rounds were carried on their person - 40 in their cartridge box and the rest in pockets or knapsack - with the rest held in their unit's wagon train. These were packed in 1,000-round cases weighing 98lbs each. A typical cavalryman rode with 40 rounds for his carbine and 20 for his pistols. For artillery it depended on the model, but the standard ammunition chest for a 12-pounder Napoleon held 32 rounds, with four chests per gun and an equal amount normally carried in the train.

Clothing & Camp Equipment
Ensuring that soldiers were adequately clothed and equipped was an immediate issue at the war's beginning, but one quickly met by Northern quartermasters. The chief clothing manufacturer and depot for the US Army was the Schuylkill Arsenal in Philadelphia, with additional depots located in other major cities. Clothing and other equipment was either manufactured in-house or bought on contract from local suppliers, then shipped out to advanced depots for further distribution; on occasion goods would be shipped directly from the factory to troops in the field.

Similar depots were set up in the South to meet the needs of the nascent Confederate army, however Southern quartermasters had much greater difficulty in their task on account of the blockade's effectiveness and the lack of domestic industry. The result was that Confederate troops often had to make do with poorer-quality material or simply go without certain items altogether. Footwear shortages in particular were persistent and had a direct effect on the army's performance (as occurred during the Maryland Campaign), while home-dyed "butternut" clothing became associated with the Confederate uniform.

Tentage was a major concern for both armies, but canvas was typically in short supply and their transportation requirements significant (an infantry company required two wagons to carry enough pre-war Sibley tents to shelter everyone), resulting in tents often being discarded. Early in the war however, the shelter-half was introduced in answer to these concerns. Carried by the individual soldier, it could be used as a sleeping bag, lean-to, or combined with another half to form a two-person tent.

Food
The Union rarely went without sufficient food for its troops, thanks to a highly effective depot system which procured and distributed the required number of rations (or, in the case of beef cattle, drove herds behind the advancing armies). Despite producing enough foods for their needs however, shortages were a frequent concern for the Confederacy due to inefficient administration and lack of transportation. Southern soldiers were more often forced to forage for their meals or hope to capture Union rations intact.

The standard daily ration for a Union soldier was 20 ounces of fresh or salt beef or 12 ounces of pork or bacon; 18 ounces of flour or 20 ounces of corn meal; 1.6 ounces of rice, or .64 ounces of beans, or 1.5 ounces of dried potatoes; 1.6 ounces of coffee or .24 ounces of tea; 2.4 ounces of sugar; .54 ounces of salt; and .32 gill of vinegar. The "marching" ration was lighter at 16 ounces of hardtack, 12 ounces of salt pork or 4 ounces of fresh meat, 1 ounce of coffee, 3 ounces of sugar, and salt. Officially the Confederate daily ration was similar with slight variations, but it was rarely issued in full due to shortages.

Medical Supplies
In both armies, the medical equivalent of a quartermaster was the medical purveyor. Purveyors were physicians responsible for acquiring, storing and distributing medicine and other supplies like surgical instruments, bandages, hospital bedding, and medical books. In the Union army, purveyors were assisted by medical storekeepers, skilled pharmacists who among other duties could act as purveyors in their absence.

Medical purveyors operated in the field or were assigned to a depot. Field purveyors were responsible for ensuring the armies they accompanied had sufficient medical supplies, while depot purveyors oversaw the purchase or manufacture of supplies, their storage, and their distribution to hospitals and armies in the surrounding area. The Union maintained two major depots in New York City and Philadelphia, with thirty subdepots established around the country. The Confederates initially set up nine districts, each with a depot, but the deteriorating military situation required many to relocate.

To address shortages and rising prices, both sides set up medical laboratories which could manufacture, test, and package medicine. Surgeon General William A. Hammond was responsible for establishing two laboratories for the Union, corresponding to the two major depots in New York City and Philadelphia. The Philadelphia lab was up and running by late April 1863, although the Astoria lab was not fully operational until February 1864. The labs likely saved the Federal government money by producing drugs at a lower cost, although the exact amount is unclear. The Astoria lab in particular was more troubled and controversial as its director was in frequent conflict with the local depot purveyor, and New York commercial manufacturers resented the competition. Both were closed shortly after the war ended.

The Confederacy established many more laboratories to meet the shortages caused by the Union blockade. While exact numbers are lost due to destroyed records, labs were known to be set up in Richmond, Virginia; Columbia, South Carolina; Arkadelphia, Arkansas; Atlanta and Macon, Georgia; Charlotte and Lincolnton, North Carolina; Mobile and Montgomery, Alabama; and possibly Little Rock, Jackson, and Knoxville. Confederate labs tended to have fewer and less quality equipment than their Union counterparts, resulting in worse quality in some of the medicine produced. Even when medicine was available, a lack in appropriate containers (jars, bottles, etc.) prevented it from being distributed. To try and address chronic shortages in vital medicines, civilians were encouraged to gather indigenous plants which could be used to make alternative remedies.

Transportation
Historian Earl Hess identified four primary means of transporting supplies during the Civil War: coastal shipping, riverboat shipping, rail transportation, and wagon trains. The first three were national in scale, being concerned with getting men and supplies close to the battlefield, and were either wholly or in part influenced by the steam engine. Wagon trains carried supplies for the last mile and accompanied armies in the field. Supplementing these were the use of pack animals, soldiers carrying their own gear, and cattle drives.

In the final fiscal year of the war (ending June 30, 1865) the Union's impressive logistics network was responsible for moving 3,982,438 passengers via rail, sea and river transport: 3,376,610 soldiers under orders, 201,106 soldiers on furlough, 256,693 prisoners of war, and 148,629 civilians. Another 716,420 animals were similarly transported: 407,848 horses; 123,448 mules; and 185,124 cattle. Lastly, a total of 9,458,871 tons of supplies were moved by various means, amounting to over 4.1 million tons of food, over 3.7 million tons of Quartermaster supplies, 1.3 million tons of Ordnance supplies, 90,000 tons of medical supplies, and 127,000 tons of miscellaneous items.

Coastal Shipping
Thanks to their dominance at sea, coastal shipping played a major role in supporting Union forces. Perhaps the biggest demonstration of this was the unprecedented ocean-borne movement of the Army of the Potomac at the start of the Peninsula campaign. Between March 17 and April 8, a fleet of 113 steamships, 188 schooners and 88 barges ferried the Army of the Potomac from Perryville, Alexandria, and Washington to Fort Monroe. Out of the 121,500 men, 14,592 animals, 44 artillery batteries, and other equipment which made up this force, only eight mules died and nine barges were lost (although their cargo was saved).

By the last fiscal year of the war, the Union's Quartermaster Department had under charter or owned outright 719 vessels: 351 steamships, 89 sailing vessels, 111 tugboats and 168 barges. The total cargo capacity of this fleet was 224,984 tons, at a daily expense of $92,414. Earlier in the war, the process of purchasing and chartering was done by individual quartermasters (many with no experience in the industry), resulting in price gouging. Greater oversight was achieved in 1863 under the efforts of Quartermaster General Meigs and in 1864 he appointed the reliable George D. Wise to oversee all coastal and inland lake shipping.

The Confederates were never able to fully utilize coastal shipping on account of the US Navy's control of the sea, but where possible attempts were made to ship goods by this route. The exact size and scope of this effort are unknown, due in part to poor recordkeeping practices. A census of all shipwrecks of the time done by W. Craig Gaines however counts a total of 280 Confederate coastal ships. Many of these losses were the result of self-sabotage to prevent them from falling into Federal hands.

Riverine Shipping
Transportation by riverboat was a central feature of the Civil War's Western Theater, dominated as it was by the Mississippi River and its tributaries, although riverboats also played a role in the East with its various rivers and canals. There were an estimated 817 steamboats in the West in 1861, and they had an advantage over railroads in their ability to carry more freight. A typical Ohio River steamer could carry 500 tons of supplies and passengers, enough to support 70,000 men and 20,000 animals for a day. Steamboats however tended to be slower, especially during the dry season when water levels fell and many were forced to reduce their cargo capacity.

As elsewhere in military logistics, the Federal government went about creating an effective river-based transportation system on a hitherto unrivaled scale. Initially the purchase or chartering of boats was done by individual quartermasters, leading to much waste and abuse, but an important step was made early in the war when Lewis B. Parsons Jr. was given oversight of all steamship transportation along the Mississippi. Parsons was effective in combating fraud and managing the steamboats along the river such that his responsibilities gradually increased until 1864 when he was put in charge of all river and rail transportation. By the end of the war's last fiscal year, the Federal government controlled 114 steamboats and 486 barges in the West, making it larger than any other steamer company.

The Confederates also utilized steamboats in the West but to a lesser extent; nor was any single officer assigned to oversee the system, leaving it to individuals to manage as best they could. The list of shipwrecks compiled by Gaines gives a total of 125 Confederate river craft, a majority of which they destroyed themselves to avoid capture. Lewis Parson's own accounting of all Western steamboats lost during the war is 327, a majority of which were due accidents.

Rail Shipping
The American Civil War was the first 'railroad war' in history, due in no small part to the fact that in 1860 the United States had over 30,000 miles of tracks, more than any other country. The typical American freight train was composed of a 4-4-0 steam locomotive pulling 17 boxcars, each capable of carrying 5 to 10 tons of freight. A typical passenger train had 10 passenger cars, each capable of comfortably seating 50 to 60 passengers. Trains could travel 50 to 60 miles on one cord of wood or one ton of coal at an average speed of up to 22.6 miles per hour, though more often they were forced to travel slower.

The Union started the war with the clear advantage in terms of rail transportation, having a majority of the nation's track milage and railroad companies. Just as important however was an effective means of administrating the vast rail network under a centralized authority to ensure supplies arrived in a timely manner. Towards this effort, Secretary of War Edwin Stanton was instrumental in hiring competent civilians with managerial experience, giving them military commissions, and allowing them to administer the railroads unhindered with the authority of the United States Military Railroad (USMRR). When the war was over the USMRR was the largest railroad conglomerate in the world with 50 rail lines totaling 2,600 miles of track, 433 locomotives and 6,650 cars.

Although the act creating the USMRR also gave the Federal government the right to seize any railroad in the country, it preferred to restrict this power to Southern roads taken in the course of the war. Instead, the government sought to work together with Northern railroad companies to meet its needs and negotiate fair rates for shipping soldiers and goods. Northern companies for their part were happy with this arrangement, partly out of patriotism, partly due to the profits they could realize, and partly from the very real threat that seizure of their roads represented.

Conversely, the Confederates were at a serious disadvantage in rail transportation when the war began. There were only 9,000 miles of track in the Confederacy and most of it ran north-south with no connecting lines. There were few factories in the south capable of producing locomotives, cars or rails, and they were incapable of meeting the demands imposed by the war: an estimated 49,000 tons of rails were needed by the South every year but it could only produce 20,000 tons total from two factories. Most railroad mechanics in the South were actually Northerners, and many promptly fled at the conflict's onset.

This state of affairs was only compounded by inefficient management of what railroad resources the South did possess. Most Southern lines were small, highly centralized and jealously guarded by their managers in the Antebellum period, meaning few had experience coordinating operations on the size necessary for the war. Although the Confederate government granted itself the authority to seize railroad property, for ideological reasons it was unwilling to do so. Aware of this, Southern companies were at an advantage in negotiations with the government for shipping rates while simultaneously giving preference to private shipping. While there were instances of efficient and timely movement of men and goods, a lack of coordination and resources were the overall themes of Confederate rail transportation.

Engineers
Military engineers performed many vital missions for both sides of the Civil War. Their tasks included constructing fortifications and earthworks; repairing and building roads, bridges and railways; demolishing obstacles both natural and man-made; and conducting reconnaissance and surveying missions to create desperately-needed maps. Professionally trained military engineers were highly valued but few in number, requiring many civil engineers to be commissioned as volunteers and help carry out the necessary work. Although complex projects such as constructing forts and pontoon bridges required the specialized skills of trained engineers, many simple tasks like clearing roads were performed by regular troops either on their own or under the supervision of an engineer. Such troops could be organized into special pioneer units.

While both sides started the war with inadequate numbers of engineering troops, the North had a larger supply of men with appropriate training: by 1860, there were seven times more carpenters, factory workers, and engineers in the North than in the South. This larger pool of skilled craftsmen allowed it to greatly increase the number of regular engineers in service and raise a number of volunteer engineering regiments. In the South meanwhile, the small number of engineering officers grew more slowly and were hampered by lack of sufficient manpower and resources such as money and iron. Slave labor could help offset this deficiency, but slaveowners were loath to lend out their workforce as doing so reduced their economic output. Even as the Confederate Congress authorized the conscription of slaves as a labor force, state and local officials continued to resist efforts to draft their slaves.

Historian Thomas F. Army argues the North's ability to sustain military operations deep within Confederate territory and thereby win the war was thanks to its large pool of trained civil engineers and mechanics, and that this advantage was not solely due to a larger population but also to a greater emphasis on public education. Northern governments recognized that an educated citizenry was not just a moral good, but necessary for the development of an industrialized economy. Common schools, agricultural fairs, lyceum meetings and mechanics' institutes led to the spread of knowledge and gave Northern workers the opportunity to improve their station in life. Thus by 1860 the 'western' states of Ohio, Indiana and Illinois boasted a combined total of 5,000 civil and military engineers, 43,000 carpenters, and 4,000 ironworkers; in comparison Virginia, North and South Carolina combined had only 1,300 civil and military engineers, 14,000 carpenters, and 880 ironworkers.

Conversely, he argues that slavery had a negative effect on Southern education and worked to limit the pool of trained engineers and mechanics available to the Confederacy. The political elite had a paternalistic worldview and made a conscious effort to limit the spread of knowledge which might cause citizens to start questioning the "peculiar institution." With few exceptions very little investment was made in public education, and what opportunities did exist were mostly focused on providing a classical education to offspring of the planter class. There were educated engineers and mechanics in the South, and even slaves were taught to become skilled craftsmen, but they were simply too few in number.

Union
When the Corps of Engineers was permanently established in 1802, chief among its responsibilities was constructing and maintaining the nation's coastal forts and running the United States Military Academy. A separate Corps of Topographical Engineers was permanently established in 1831 specifically with the mission of mapmaking. Both however were too few in number when war broke out: the Corps of Engineers numbered only 48 officers (eight of whom resigned to join the Confederacy) and a single company of engineer troops, while the Topographical Engineers numbered 45 officers (of whom seven resigned). Congress resisted recruiting more engineers at first as their pay was much greater than normal troops, but after the disaster of First Bull Run, they authorized an expansion of both corps and the recruitment of three more engineer companies, together forming the US Engineer Battalion (later renamed the 1st Engineer Battalion). As their mission largely overlapped each other, Congress eventually merged the Topographical Engineers into the Corps of Engineers in 1863 and expanded its size to 105 officers.

This was still not enough to meet the engineering needs of the Union, and so with reluctance Congress agreed to accept volunteer engineer troops in October 1861. Among the first to be accepted were the 15th New York Engineer Regiment and 50th New York Engineer Regiment, which together with the US Engineer Battalion formed the Volunteer Engineer Brigade for the Army of the Potomac. Additional volunteer engineer units would serve in the Western theater, including the Engineer Regiment of the West, the 1st Michigan Engineers and Mechanics Regiment, and Patterson's Independent Company Kentucky Volunteer Engineers.

Further supplementing the regular and volunteer engineers, line units were sometimes assigned to specific engineering projects or to carry out engineering duties for specific lengths of time; this was more common in the West were engineers were fewer in number. For example, during the Vicksburg campaign, Company I of the 35th Missouri regiment was designated as the Army of the Tennessee's pontoon company. Line units would also detail soldiers from within their ranks to form company-sized detachments of pioneers or combine them into a "pioneer corps" for their parent division. Many Black laborers were also hired to perform pioneer duty.

Confederacy
The Confederate Corps of Engineers was established in March 1861 with just five officers and a company of 100 troops; in May that number was increased to 20 officers and a second company for 200 troops. Too few of a force even in peacetime, Judah P. Benjamin convinced the Confederate Congress to authorize the creation of a Provisional Corps of Engineers in December. Meant to last for only the duration of the war, it was initially authorized 50 officers (no higher in rank than captain) before being doubled in April 1862 and the rank limitation removed by the end of the year. Unfortunately in the eyes of Jeremy F. Gilmer, chief engineer of the Confederacy, only 20 of the Provisional Corps officers could rightfully be called engineers, while many of the rest were not worth their pay. To compensate for this deficiency, he was able to convince Congress to increase the number of regular engineer officers to 120 in 1863, and to gradually increase his budget, from a paltry $1 million in 1861 to $20 million by 1864.

While the Confederates made every effort to recruit engineer officers into their ranks, they were less diligent in recruiting engineer troops. In December 1862 Gilmer proposed the creation of four engineer regiments, to be split between four theaters of operation: the Gulf and Atlantic coast, the Mississippi Valley, Tennessee, and the Army of Northern Virginia. Congress approved this plan in March 1863, and recruitment began in May: troops were to be recruited from among the army ranks (each company sourcing from a single division) while officers were to already hold commissions within the Engineer Corps or be line officers with engineering experience. Robert E. Lee put a temporary hold on recruiting in the aftermath of the Battle of Gettysburg however, fearful it would weaken his already depleted forces, until a compromise could be reached.

The 1st Confederate Engineers regiment joined the Army of Northern Virginia by Spring 1864, although it did not compare favorably to its Union counterparts: only five of the regiment's eleven companies could build a pontoon bridge, versus every company in the Volunteer Engineer Brigade being trained to do so, and only one in ten men were classified as skilled craftsmen and artisans (artificers), against which one in four among the 15th New York Engineers were so ranked. The 2nd Confederate Engineers existed in name only, with just two companies raised, and so fell under the command of the 1st Engineers. The 3rd Confederate Engineers joined the Army of Tennessee in late spring 1863, but only eight of the intended nine companies were raised, and only five could be considered effective bridge builders. The 4th Confederate Engineers was formed in the summer of 1864 but could only muster three companies, was scattered across the Trans-Mississippi Department, and eventually broken up early the next year. A further eight undersized companies were formed and spread out across the southeast under the command of local officers.

As with the Union Army, the rebels relied heavily on regular infantry and Black laborers to do much of the actual engineering work. Units of designated pioneers were created on an informal basis by brigade commanders early in the war, until the practice was institutionalized in January 1863 by President Davis, with General Lee designating a pioneer company for each division. Black workers, both free and enslaved, were impressed to build fortifications protecting Southern cities. A formal process for impressing slaves to work for the Confederacy was instituted in March 1863, setting terms for length of service and compensation owed to slaveowners, but it was unpopular amongst the owners as their workforce was sorely missed during planting and harvesting season. When Davis ordered the hiring or impressment of 20,000 slaves in February 1864, it brought in thousands of new workers to shore up the defenses of Richmond and Atlanta, but created so much resentment that several state officials refused to help implement the order.

Communications
Military communications during the Civil War was a unique mix of time-tested methods and brand-new technologies. Couriers, whether that be a staff officer on horseback or a runner on foot, were the principal form of tactical communications on the battlefield. Supplementing them were optical communication methods, including flags, flares or torches, although these were chiefly used at the operational level of war. Perhaps the most transformative was electrical telegraphy, which allowed instantaneous communication across vast strategic distances, although it could be used at the operational and even tactical levels.

Recognizing the importance of communications, both sides set up their own signal corps to handle this vital function. Major Albert J. Myer had lobbied for and been appointed to lead the US Army's Signal Corps in 1860. Although the Signal Corps consisted of just Myer at first, it eventually grew to a force of thousands by war's end. However, Myer's attempt at assuming greater control over field telegraphy put him in contention with the U.S. Military Telegraph Corps and its patron Secretary of War Stanton, who relieve Myer of duty in November 1863. Meanwhile Edward Porter Alexander, who had been Myer's assistant, helped form a Confederate Signal Corps in April 1862 which grew in size to rival its Union counterpart.

The use of couriers was often the most or only viable method of communication on the battlefield, but it could be fraught with many difficulties. Assuming the messenger wasn't killed, captured, or otherwise delayed on their mission, the message might be misinterpreted, or the situation might have changed such that the message was no longer relevant. These problems were well illustrated during the Vicksburg Campaign. At the Battle of Champion Hill, General Grant issued an order to John A. McClernand to bring his corps into action against the enemy, but because the courier chose to travel by road instead of cross-country the order was delayed by four hours. Another danger was demonstrated before the battle on May 13 when Joseph E. Johnston issued orders to John C. Pemberton to move his troops: one of the three messengers sent was actually a spy who delivered the message to Grant instead!

The wigwag flag signaling system was used by both sides of the conflict; unsurprising as it had been developed by Myer with Alexander's help. Signal stations would be set up on the highest point of terrain or atop specially constructed signal towers, creating a chain of stations along which messages could be sent. Such exposed positions allowed signalers to report on any enemy movement while simultaneously putting them in constant danger of being picked off by snipers or artillery. The nature of these messages also meant the enemy could read them as well, necessitating the early use of encryption. Because the navy used a different flag signal system, army officers would be stationed on ships to help coordinate naval gunfire support. Colored lights and rockets, or signal guns, could also be used to transmit prearranged messages to commanders.

An extensive telegraph network had been constructed in the United States prior to the war, and so both sides started with relatively equal capabilities. However the South lacked the resources to produce additional telegraph wires and so could not expand their network. Electrical telegraphy allowed for direct and immediate communication between the different field armies and their respective capitals, even down to individual corps commanders. Telegraph lines could be cut though, or the enemy could "tap" into the line directly, requiring the use of encryption here as well. Myer had attempted to expand the role telegraphy played on the battlefield with the adoption of the Beardslee Telegraph, but when he was sacked by Stanton this effort was abandoned.

Medical support
The state of military medicine during the Civil War was poor in the beginning on account of inadequate administrative planning and lack of medical knowledge. The pre-war Medical Department was ill-equipped to deal with the sudden influx of vast numbers of citizen-soldiers and its Confederate counterpart had to be created from scratch. Screening recruits for pre-existing conditions was poorly done; a lack of education in field hygiene and sanitation meant large gatherings of soldiers (many unaccustomed to adverse environmental conditions) became breeding grounds for diseases; and concepts such as aseptic surgery or germ theory were largely unknown. Improvements were made during the war, but in the end twice as many soldiers died of disease as from actual combat.

Both medical departments were similarly organized, headed by a surgeon general with a small administrative staff. Each field army was assigned a medical director who reported directly to the surgeon general and were responsible for ensuring their army's medical needs were met. Each subordinate unit down to the brigade level was also assigned a medical director, while each regiment was assigned a surgeon and one to two assistant surgeons. Northern medical directors also had responsibility for the hospitals within their area of operations, while in the South the separate position of medical director of hospitals was established. Additional personnel included medical inspectors who audited the medical system and medical purveyors charged with acquiring and distributing medicine.

Neither side possessed a formal system of casualty evacuation at the start of the war. Hired civilian ambulance drivers proved to be insubordinate, and while a wounded soldier's fellows could help him off the battlefield, doing so removed them from the fight as well. Musicians pulled double duty as stretcher bearers, but their performance in this role was inconsistent. William A. Hammond and Jonathan Letterman were ultimately responsible for creating the U.S. Ambulance Corps which effectively solved the problem for the Union. The Confederates also set up a similar corps, but shortages in ambulances and animals to pull them made the task more difficult. Initially, battlefield casualties were transported to a field hospital set up by their regiment's surgeon and assistant surgeons in a nearby tent, house, or stand of trees; the staff included a hospital steward, and whatever nurses, cooks, and laundresses were available. This proved insufficient as some regimental hospitals could easily become overwhelmed while others may refuse to treat casualties from a different regiment. After Second Bull Run, Hammond and Letterman were responsible for consolidating field hospitals at the division or sometimes corps level, ensuring there were enough surgeons and staff to see to the patients' administrative and medical needs. The Confederates would also consolidate field hospitals at the brigade or division after the early part of the war.

If a soldier required further care or convalescence after being treated by the regimental surgeon or at a field hospital, and they could travel, they would be sent to a general hospital well behind the lines. There had been few hospitals in the United States prior to the war as most people preferred to be treated at home, but with the scale of the conflict many were established in towns and cities North and South. In addition to general hospitals which treated all patients and ailments, many specialty hospitals were also set up, such as ones reserved for officers or which treated specific diseases (i.e. "pest" hospitals dedicated to smallpox). Receiving and distributing hospitals, also called depot or clearing hospitals, served as triage centers which provided short-term care before patients were assigned to another hospital. Wayside hospitals were established along common transportation routes to provide a rest area with food and minor medical care for soldiers in transit. The movement of patients and convalescents between these locations was handled by dedicated hospital trains and hospital ships where possible.