The men they fought to free . A black soldier tends a wounded federal soldier . A wounded soldier left in a deserted camp is tended by a black comrade , another striking picture of the Civil War taken by Matthew Brady . Black soldiers served on both sides , for the North as soldiers , for the South as labourers , followers , officers servants . Emancipation of the black slaves in the South was one of the most important resu;ts of the war , although its immediate cause was secession of the Southern States from the Union