Short answers, pulled from the story.
The United States Colored Troops were Union Army regiments primarily composed of African American soldiers, with men from other ethnic groups also serving. By the war's end in 1865, 175 USCT regiments had formed, comprising more than 178,000 free Black men and freedmen and constituting about one-tenth of the Union Army's manpower.
Approximately 20.5 percent of USCT soldiers died from all causes, compared to 15.2 percent of white Union volunteers, a mortality rate about 35 percent higher. Over 36,000 of the approximately 180,000 USCT soldiers enrolled died, with disease causing the majority of fatalities.
The U.S. War Department established the Bureau of Colored Troops through General Order Number 143, issued on the 22nd of May 1863. The bureau oversaw recruitment of African American soldiers into infantry, cavalry, engineer, and artillery units across all Union states.
The Confederate Congress passed a law on the 1st of May 1863 declaring that Black soldiers captured in Union uniform would be tried as rebellious slave insurrectionists, a capital offense. In practice, USCT soldiers were frequently murdered by Confederate troops without trial, most notably at Fort Pillow in Tennessee, the Battle of the Crater in Virginia, and the Battle of Olustee in Florida.
Sixteen to eighteen African American USCT soldiers received the Medal of Honor for Civil War service. Recipients included Sergeant William Harvey Carney of the 54th Massachusetts for his actions at Fort Wagner in July 1863, and fourteen soldiers, among them Sergeant Major Christian Fleetwood, for the Battle of Chaffin's Farm in September 1864.
The USCT was disbanded in the fall of 1865. Many veterans were drawn into the reorganized Regular Army, serving in the 9th and 10th Cavalry and the Black infantry regiments authorized in 1867. Deployed in the American West from 1870 to 1898, these soldiers became known as the Buffalo Soldiers.