The brigade traces its origins to the British Army of the 15th century as a temporary formation to control multiple regiments when necessary.
The US Army also maintained this status until the middle of the 20th century, when the first permanent brigades were formed.
Brigades were numbered based on their position within their parent division, but could also acquire nicknames even when this designation changed.
Instead, these duties were carried out soldiers and non-commissioned officers detailed from their subordinate units or hired civilian laborers (including so-called "contraband" or freed slaves).
[4] When a brigade was deployed in a battle line, the standard spacing was twenty-two paces between regiments, although in actual practice such intervals were rarely maintained.
[6] However, early in the war individual cavalry regiments were attached to infantry divisions to be used as their commander saw fit, often as escorts, orderlies and pickets.
However this only served to dilute their firepower as demonstrated at the First Battle of Bull Run, after which they were reassigned from brigades to divisions.
[8][11] During World War I, the United States Army formed its divisions as square divisions of four infantry or cavalry regiments in two infantry or cavalry brigades and three artillery regiments in one artillery brigade.