On the eve of the Civil War, there were few officers of the US Army who had ever seen so much as a brigade gathered together in one place. The Regular Army was tiny and its troops were mostly scattered in small detachments at forts and frontier posts. But with the outbreak of war in 1861, armies of a size never before seen in North America took the field. The largest, the Union's Army of the Potomac, was the creation of Major General George B. McClellan, nicknamed "the Young Napoleon." Despite McClellan's talent for military organization and training, he proved no match as a commander for Robert E. Lee, but the army he built was destined to carry the cause of the Union to victory.

McClellan's organizational scheme for the infantry followed the model established by Napoleon's Grand Army. The basic tactical unit was the infantry corps, composed of three or four divisions, each divided into three or four brigades, plus an artillery brigade, for a total strength of 10,000-15,000 men. The complexity of this organization gave rise to a need for badges or insignia that would permit quick identification of units and mark the locations of commanders on the battlefield. Corps badges, usually authorized by corps commanders, began to appear in 1862, and they soon were placed on flags. Finally, General Orders No. 53 Army of the Potomac (May 1863) introduced a standard system for that army. Each corps was allotted a distinctive badge. The corps distinguishing flag was blue, swallow-tailed, and displayed the badge plus the number of the corps. Flags for divisions and brigades were rectangular and triangular respectively, with a distinctive color scheme for each. There were also flags for the corps artillery brigade and the corps quartermaster.

Other Union armies and military departments adopted similar systems for distinguishing flags, but no Army-wide regulation governing their design was published during the Civil War. Nevertheless, the shoulder sleeve insignia and organizational flags of today's US Army can trace their origins back to these corps insignia and flags.

Each regiment of the Army received a National Color and a Regimental Color. The former was a fringed version of the Stars & Stripes inscribed with the regimental title. The latter was dark blue with the national coat of arms over a scroll inscribed with the title of the regiment. Several different designs were used for the Regimental Color and many regiments carried a state flag instead.  Regiments also had flank marker flags and these were variable in design. Companies and batteries had general guide flags (guidons), most often of the Stars & Stripes pattern.

See also US Army: Organizational Flags for Field Armies, Corps & Divisions


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I Corps
Army of the Potomac
II Corps
Army of the Potomac
XIV Corps
Army of the Cumberland
Cavalry Corps
Army of the Cumberland



XXIV Corps
Army of the James
Corps Flags
United States Colored Troops
Regimental Colors & Flags

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