Wikipedia:WikiProject Military history/Academy/Writing an Order of Battle

An order of battle (OOB, O/B or ORBAT) is a form of organisation chart used to detail the personnel involved in military events. Despite the name, an order of battle is not limited to single battle situations, but can also represent the involvement of armed forces in larger campaigns or theatres of war.

Orders of battle are structured depending on the units involved. For example, an army will normally consist of a command unit plus infantry, cavalry and artillery formations. The detail regarding each formation may depend on the scale of the conflict. A large-scale campaign may start with armies and their subordinate corps, whilst a small campaign or battle force may only involve divisions and brigades.

An order of battle should indicate the number of troops in the entire force and per formation at the outset, or at a specific point of a lengthy campaign, with artillery units typically specifying number of guns. Each formation should usually detail its commander, by name and rank. The force will have been led by an overall commander, for example Napoleon I, Robert E. Lee, Dwight D. Eisenhower, or possibly an officer of lower rank for less notable battles perhaps commanding a detachment, who should be noted before anyone else.

In modern military organisations an order of battle may also include naval or aviation formations, as well as technological land units such as tank corps. An order of battle aims to detail an army so that it may be compared with the opposition's order of battle by readers. By understanding who was involved in an event, and the units at their disposal, the development and outcome of many military engagements are better understood. A series of orders can act as a timeline, indicating losses or reinforcement during the course of a campaign where many battles have taken place. Being able to follow well cited numbers is valuable data to many military historians, and requires careful research.

Introductory materials in an order of battle should summarise the conflict the units are involved in, and give a brief account of where the forces came from prior to the campaign or action. The order can be further embellished with notes describing particular sub-unit participation in the action.

Naval orders of battle for actions during the Age of Sail should generally present the ships in the line of battle sequence, and list the ships carrying the flag officers of the fleet. If the line of battle was not actually followed in the battle this should be noted (for example, if the fleet wore and thus reversed the sequence before the battle began). Casualty information should be broken down by ship if possible.

As with other articles, orders of battle should be referenced to reliable sources. Examples of high quality orders of battle can be found at Wikipedia:Featured lists.