African Americans were very involved in the Vietnam War, even more than their proportion in the population as a whole. This was due in part to the fact that the draft originally exempted college students and African Americans were less likely to go to college than whites were.
Racism also played a part in the role that blacks played in this war. They made up 14% of all military personnel in the the Vietnam War yet they accounted for (as an example) 25% of the personnel killed in the years 1965 and 1966. This is due to the fact that African Americans were more likely to be put in combat units than people of other races were.
African Americans, then, played more of a role in the fighting of the war than might have been expected given their numbers in society. To its credit, the military became one of the parts of society in which African Americans were most likely to be able to advance and to be treated fairly in they years during and after Vietnam.