This is the story of the most famous unit in the Union Army. Originally called the "Black Hat Brigade" because the soldiers wore the army's regular dress black hat instead of the more typical blue cap, the Iron Brigade was the only all-Western brigade in the Eastern armies of the Union. The Brigade was initially made up of the 2nd, 6th, and 7th Wisconsin and the 19th Indiana Volunteers; later it was reinforced by the 24th Michigan Volunteers. Battery B of the 4th U.S. Artillery, consisting in large part of infantry detached from the brigade, was closely associated with it.