Order of battle

In modern use, the order of battle of an armed force participating in a military operation or campaign shows the hierarchical organization, command structure, strength, disposition of personnel, and equipment of units and formations of the armed force. Various abbreviations are in use, including OOB, O/B, or OB, while ORBAT remains the most common in the United Kingdom. An order of battle should be distinguished from a table of organisation, which is the intended composition of a given unit or formation according to the military doctrine of its armed force. As combat operations develop during a campaign, orders of battle may be revised and altered in response to the military needs and challenges. Also the known details of an order of battle may change during the course of executing the commanders' after action reports and/or other accounting methods (e.g. despatches) as combat assessment is conducted.

Historical approaches

In its original form during the Medieval period of European warfare, an order of battle was the order in which troops were positioned relative to the position of the army commander. The term was also applied to the disposition of ships in the line of battle during the age of sail. In the later transformation of its meaning during the European period of Early Modern warfare the order of battle came to mean the order in which the units manoeuvered or deployed onto the battlefield to form battle-lines, with the positioning on the right considered the place of greatest honour. This need to reflect the unit seniority led to the keeping of military staff records, in tabular form reflecting the compilation of units an army, their commanders, equipment, and locations on the battlefield.