The true statement about African American soldiers during the Civil War is:
They were used to fill the ranks in regiments left by deceased white soldiers.
While African American soldiers did face challenges related to equal treatment and were sometimes assigned to menial tasks, they eventually played a significant role in combat, particularly after the Emancipation Proclamation in 1863. However, it is important to note that they were not usually led by African American officers; most regiments were led by white officers. Enlistment also increased significantly after the initial years of the war rather than at the very start.