By early 1863, voluntary enlistments in the Union army had fallen so sharply that the federal government instituted an unpopular military draft and decided to enroll black, as well as white, troops. Indeed, it seems likely that it was the availability of large numbers of African American soldiers that allowed President Lincoln to resist demands for a negotiated peace that might have including the retention of slavery in the United States. Altogether, 186,000 black soldiers served in the Union Army and another 29,000 served in the Navy, accounting for nearly 10 percent of all Union forces and 68,178 of the Union dead or missing.

Three-fifths of all black troops were former slaves. The active participation of black troops in the fighting made it far less likely that African Americans would remain in slavery after the Civil War.

While some white officers, like Robert Gould Shaw (1837-1863), who commanded the 54th Massachusetts Regiment, were proud to lead black troops in battle, others exhibited a deep resistance.

Blacks in Blue by Steven Mintz, The Gilder Lehrman Institute of American History