User:Gog the Mild/Cog / Cog (military)



A cog is a type of ship that first appeared in the 10th century, and was widely used from around the 12th century on. Cogs were clinker-built, generally of oak. This vessel was fitted with a single mast and a square-rigged single sail. These vessels were mostly associated with seagoing trade in medieval Europe, especially the Hanseatic League. Typical seagoing cogs ranged from about 15 to 25 meters (49 to 82 ft) in length with a beam of 5 to 8 meters (16 to 26 ft) and were 30–200 tons burthen. Cogs were rarely as large as 300 tons although a few were considerably larger, over 1,000 tons.

Although the name cog is recorded as early as the 9th century, the seagoing vessel of that name seems to have evolved on the Frisian coast during the 12th century. Cogs progressively replaced Viking-type ships in Northern waters during the 13th century. Why this was the case is uncertain but cogs could carry more cargo than knarr of a similar size. Their flat bottoms allowed them to settle flat in harbour, making them easier to load and unload. Their high sides made them more difficult to board in a sea fight, which may have made them safer from pirates.

Cogs were also used as military transports and warships, fitted with towers fore and aft.

Description and construction
Cogs were a type of round ship, characterized by a flush-laid flat bottom at midships which gradually shifted to overlapped strakes near the posts. They were propelled by a single, large, rectangular sail. Typical seagoing cogs ranged from about 15 to 25 meters (49 to 82 ft) in length with a beam of 5 to 8 meters (16 to 26 ft) were 40–200 tons burthen, although a very small number were considerably larger, over 1,000 tons. A rule of thumb for crew size was that one sailor, exclusive of any dedicated fighting men, was required for every 10 tons burthen of the cog, although this may generate a suggested crew size on the low side of Medieval practice. The crews of cogs pressed into military service were usually increased. Craig Lambert argues that this was because after fulfilling any transport role they were expected to take an "active naval role and harr[y] the coast and enemy shipping." Crews of up to 45 for civilian cogs are recorded, and 60 for a 240 ton cog being used for military transportation.

Cogs were typically constructed largely of oak, and had full lapstrake, or clinker, planking covering their sides, generally starting from the bilge strakes, with double-clenched iron nails for plank fastenings. At the stem, chases are formed; that is, in each case, the land of the lower strake is tapered to a feather edge at the end of the strake where it meets the stem or stern-post. This allows the end of the strake to be fastened to the apron with the outside of the planking mutually flush at that point and flush with the stem. This means that the boat's passage through the water will not tend to lift the ends of the planking away from the stem. Before the next plank is fitted, the face of the land on the lower strake is bevelled to suit the angle at which the next strake will lie in relation with it. This varies all along the land. The new strake is held in position on the preceding one before the fastening is done. The keel, or keelplank, was only slightly thicker than the adjacent garboards and had no rabbet. Both stem and stern-posts were straight and rather long, and connected to the keelplank through intermediate pieces called hooks. The lower plank hoods terminated in rabbets in the hooks and posts, but upper hoods were nailed to the exterior faces of the posts. Caulking was generally tarred moss that was inserted into curved grooves, covered with wooden laths, and secured by metal staples called sintels. The cog-built structure would be completed with a stern-mounted, hanging, central rudder on a heavy stern-post, which was a uniquely northern development. The single, thick, mast was set forward of amidships, stepped into the keelplank and equipped with a single large, rectangular, square-rigged sail. The masts of larger vessels would be of composite construction. Complicated systems of rigging were developed to support the mast and to operate the sail. Cordage was usually hemp or flax and the sail hemp-based canvas. From the 13th century cogs would be decked, and larger vessels would be fitted with a stern castle, to afford more cargo space by keeping the crew and tiller up, out of the way; and to give the helmsman a better view.

A cog, compared with the carvel-built vessels more traditional in the Mediterranean, was expensive and required specialist shipwrights. However, their simpler sail setup meant that cogs only required half the crew of similar sized vessels equipped with lateen sails, as was common in the Mediterranean. A structural benefit of clinker construction is that it produces a vessel that can safely twist and flex around its long axis (running from bow to stern), which is an advantage in North Atlantic rollers, provided the vessel has a small overall displacement. A further limitation of cogs is that they lack points to mount additional masts At least some fore-and-aft sails are desirable for manoeuvrability. Clinker-built cogs were effectively limited to a single sail. This made them unhandy, limiting their ability to tack in harbour and making them very reliant on wind direction at the start of voyages. The flat bottom permitted cogs to be readily beached and unloaded at low tide when quays were not available; a useful trait for both trading and military purposes. Cogs were expected to have a working life of approximately 40 years.

History


The classic cog, with a rear-mounted rudder, is first mentioned in 948 AD. These early cogs were influenced by the Norse knarr, which was the main trade vessel in northern Europe at the time, which used a steering oar. The initial impetus to further development was the silting up of the Limfjord, which meant that ships entering or leaving the Baltic needed to be seaworthy enough to reliably make the dangerous trip round the north of the Danish Peninsula. This caused a boom in the number of small cogs, and the need for spacious and seaworthy ships led to the development of the cog as the workhorse of the Hanseatic League. It soon became the main cargo carrier in Atlantic and Baltic waters. Cogs could carry more cargo than knars; the rudder made steering easier than did the steering oar of the knar, especially for larger vessels; and cogs were cheaper to build. The latter was due to the cog's use of sawn, rather than split, timber. By the 12th century cogs were the most common vessel in the Baltic and the Atlantic.

The mid-14th-century chronicler Giovanni Villani reported in 1304 a fleet of cogs from Bayonne raided into the Mediterranean, where cogs had not previously been noted. The Mediterranean maritime powers hurried to build cogs of their own. This led to a Mediterranean variant, the cocha.

Towards the end of the 14th century the cog was increasingly replaced by the hulk.

By the end of the fifteenth century, cogs were rarely converted for fighting use, as purpose built "great ships", equipped with two or three masts and guns, had taken over this role.

Conversion to military use


There was no separation of cogs into specialised merchant or military categories. All cogs could be used for military use, and the occasional cog built or acquired for primarily military use would be used as a trading vessel during times of peace. The majority of seagoing cogs were 30–60 tons burthen. These were of limited use for military purposes, either as fighting vessels or as transports. Ships of approximately 50 tons and larger could be used to transport horses, and those of 60 tons or more could be adapted so as to be more effective as fighting vessels. The latter involved constructing wooden "castles" at the rear (stern castles) and front (fore castles) of the ship, increasing the height of the fighting platform and providing crenellations. Slightly larger vessels would also have crow's nests added towards the top of their masts (top castles). Sometimes top castles were improvised by hoisting small boats to the tops of masts. Observers have described fleets of cogs fitted with crenelated stern, fore and top castles as seeming "like a line of castles".

The historian Graham Cushway has suggested that once installed, castles would not readily be removed as they were as useful as defensive structures when the cogs were used as merchant carriers as when they were used as when they were impressed as fighting ships. The modern consensus is that they were removed, with the exception of any pre-existing stern castles; if nothing else, these structures would cause significant additional leeward drift for vessels already limited to sailing no closer than 60° to the wind.

height, especially, was a critical advantage in naval warfare during the Middle Ages.(Friel, “Oars, Sails and Guns,” 71. Fernandez-Armesto, “Naval Warfare,” 236.) Height was particularly advantageous for the archers and crossbow men.(Runyan, “Cog as Warship,” 50.) These factors made the ships more difficult to attack.(Kelly DeVries, Medieval Military Technology (Toronto, 1992), 304.)

Military transport


Those ships carrying horses were outfitted especially for the task with hurdles placed between the horses and the ships fitted with slings, not to mention special gangways for loading and unloading the horses. In addition to special gangplanks, horses also were loaded and unloaded via windage in which the horse was fitted with a sling and raised or lowered by means of ropes and pulleys.270 The two methods likely reflect the variety of shipping employed and suggest that some vessels were not (or could not be) adapted to allow the use of gangplanks; therefore, windage would have been a necessary alternative. The cogs used for transportation were usually drawn from the general stock of merchant ships, which meant that they suffered from their small carrying capacity; for example, throughout the Hundred Years' War (1337–1453) the average number of men per cog transported by the English was 12. This only increased when horses were not included, but this severely restricted the mobility of the force being shipped on its arrival.

Ayton, Knights and Warhorses, 125.

Ann Hyland, the medieval warhorse

Examples of military use
Pointed iron bars or boulders would be thrown from the top castles, both as anti-personnel weapons, and in the hope of holing enemy ships.

The "enormous" 300 ton cog Alderhallbencog, constructed before 1338, carried ribauldequin; when pressed into the king's service she became the first English royal ship to carry gunpowder weapons. By the start of the 15th century the use of firearms as anti-personnel weapons was common on larger ships.

Battles - Damme, Sluys, Winchelsea, La Rochelle

Transport - Damme, Gascony, 1346, Seige of Calais

It was very difficult to intercept a hostile fleet at sea, and so almost all naval battles were fought in or near ports, or at least close to the coast. A rare exception was the Battle of Winchelsea, when a force of large converted cogs under King Edward III of England successfully intercepted, largely due to good intelligence, a fleet of even larger piratical, Castilian ships. The Castilians lost over a dozen ships captured, while the English lost at least two ships sunk, apparently after contacting Castilian vessels so forcefully while boarding that they sprung their planks. If the comparatively robustly constructed cogs could sink so readily during operations in the open sea, it was a lesson on the fragility of all vessels of the period.

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