After the Emancipation Proclamation, it wasn’t uncommon at all for African American men to fight for the Union in the Civil War. In fact, almost 180,000 African American soldiers fought in the Civil War, accounting for about 10% of the Union Army during the War. African American women weren’t allowed to fight for the Union, but many served as nurses, unofficial spies, and scouts throughout the War. In the end, the African American soldiers greatly helped the Union defeat the Confederacy and 16 African-American soldiers were actually awarded the Medal of Honor.
For more information on African American’s in the Civil War, go to this website: http://www.archives.gov/education/lessons/blacks-civil-war/