It was during this battle that Fourth Brigade of First Division, First Corps earned its nickname of the “Iron Brigade” when Major General George McClellan stated that the men of Fourth Brigade “must be made of iron” while observing their movement along Hagerstown turnpike. During this engagement, Fourth Brigade began by steadily driving back two confederate regiments until they were reinforced by three more regiments. At this point, Gibbons deployed his regiments so that he would not be outflanked by the enemy and held the ground his brigade had gained until relieved by Brigadier General Gorman’s Brigade during the night. By pushing back the enemy and maintaining the ground they fought over, the “Iron Brigade” played a key role in the victory over the Confederates during the Battle of South Mountain. It is during this battle that the Brigade began to distinguish itself, a trend that would continue into their next engagement, the Battle of