The Corps d'Afrique, one of many Louisiana Union Civil War units, was formed in New Orleans after the city was taken and occupied by Union forces. It was formed in part from the Louisiana Native Guards. The Native Guards were former militia units raised in New Orleans, who were property-owning free people of color (gens du couleur libres).

Free mixed-race people had developed as a third class in New Orleans since the colonial years. During the Civil War, many of the free men of color wanted to prove their bravery and loyalty to the Confederacy like other Southern property owners, but the Confederates did not allow them to serve and confiscated the arms of those in the militia. The Confederates believed that enlisting black soldiers would hurt agriculture, as most African Americans were enslaved workers. Since the Louisianan units were composed of freeborn creoles and black freemen, it was clear that the underlying objection was to having black men serve at all.

For later units of the Corps d'Afrique, the Union recruited freedmen from the refugee camps. Liberated from nearby plantations, they and their families had no means to earn a living and no place to go. Local commanders, starved for replacements, started equipping volunteer units with cast-off uniforms and obsolete or captured firearms. The men were treated and paid as auxiliaries, performing guard or picket duties to free up white soldiers for maneuver units. In exchange their families were fed, clothed and housed for free at the Army camps; often schools were set up for them and their children.

Despite class differences between free people of color and freedmen, the troops of the Corps d'Afrique served with distinction, including at the Battle of Port Hudson and throughout the South. Its units included:
4 Regiments of Louisiana Native Guards (renamed the 1st–4th Corps d'Afrique Infantry, later renamed as the 73rd–76th US Colored Infantry on April 4, 1864).

1st and 2nd Brigade Marching Bands, Corps d'Afrique (later made into Nos. 1 and 2 Bands, USCT).
1st Regiment of Cavalry (1st Corps d'Afrique Cavalry, later made into the 4th US Colored Cavalry).
22 Regiments of Infantry (1st–20th, 22nd, and 26th Corps d'Afrique Infantry, later converted into the 77th–79th, 80th–83rd, 84th–88th, and 89th–93rd US Colored Infantry on April 4, 1864).
5 Regiments of Engineers (1st–5th Corps d'Afrique Engineers, later converted into the 95th–99th US Colored Infantry regiments on April 4, 1864).
1 Regiment of Heavy Artillery (later converted into the 10th US Colored (Heavy) Artillery on May 21, 1864).