At the beginning of the Civil War, President Abraham Lincoln realized the dire necessity of keeping the border states (slave states which did not secede) in the Union, and so he initially rejected attempts to arm blacks or emancipate slaves.  That situation had changed by the summer of 1862 as the number of white volunteers dwindled, the number of contrabands (escaped slaves under Union military protection) rose, and the border states became more secure for the Union.  In July 1862, Congress authorized the use of black men in the Union military, and President Lincoln informed his cabinet that he would soon proclaim the emancipation of slaves in Confederate territory.

The use of black servicemen, like the Emancipation Proclamation (January 1, 1863), stirred considerable opposition throughout the Union states because of racial prejudice. Black servicemen were segregated from whites in special "colored" units under the leadership of white officers, such as Colonel Robert Gould Shaw of the 54th Massachusetts Colored Infantry.  (The United States armed forces were not desegregated until the 1950s.) 

At first, black servicemen were also paid less than their white counterparts of equal rank; a net pay of $7 per month versus $13.  Harper's Weekly editor George William Curtis wrote editorials and joined Colonel Shaw, his brother-in-law, to lobby Congress for the equalization of wages.  Congress finally complied in June 1864 with an equal pay act, which was made retroactive to cover the previous years of service as well. 

A more severe problem was the Confederate policy of treating captured black servicemen and their white commanders more harshly than captured white troops. This prompted President Lincoln's threat of reprisals against Confederate prisoners of war.  It may have constrained some of the more outrageous behavior by the Confederates, but the unequal treatment of black servicemen continued.  The Confederacy's refusal to acknowledge captured black servicemen as legitimate prisoners of war undermined prisoner-of-war exchanges.  

Almost 200,000 black men served as soldiers, sailors, or laborers for the Union forces during the Civil War.  Racial prejudice meant that black men were underutilized in combat, but they still made major contributions in battles such as Milliken's Bend and Port Hudson, Louisiana; Nashville, Tennessee; and, Petersburg, Virginia.  The unsuccessful but heroic assault on Fort Wagner, South Carolina, by the 54th Massachusetts Colored Infantry is memorialized in a monument at Boston Commons and the 1989 film Glory. Nearly 80 black men were commissioned as officers during the Civil War, and 16 black soldiers were awarded the Medal of Honor.  Some black women, although not formally part of the armed forces, assisted the Union cause as nurses, scouts, or spies, including Harriet Tubman, a scout for the 2nd South Carolina Volunteers.  

Throughout history, military service, especially in battle, was often seen as a rite of passage that turned boys into men. Physical scarring or maiming served as the visible symbol of manhood tested and earned through combat. The message of this cartoon, appearing at the end of the Civil War, is that white and black Union soldiers have made the same sacrifice and are equal in their manhood. It can be inferred that, for the artist, the equality of manhood encompasses the economic right to work as free men and to provide for their families. The artist’s intent on the more difficult questions of political and social equality is uncertain, although such racial equality was advocated by Curtis on the editorial page.