Which best shows the contribution of african ammerican troops during the civil war?

a. first battle of bull run
b. second battle of bull run
c. battle of chancellorsville
d. battle at fort wagner

D. BATTLE AT FORT WAGNER shows the contribution of African American troops during the civil war.

The assault on Fort Wagner, South Carolina, by the 54th Massachusetts Infantry on 18th July 1863 ended in defeat but it showed their valor which spurred further recruitment for African American soldiers. The recruitment increased their numbers and gave the Union a numerical military advantage from a large segment of the population over the Confederates.