The Army of the Potomac under Major General George McClellan advanced north to Frederick,Maryland and on the fourteenth day of September, pitched battles occurred for the possession of the three gaps in South Mountain, a continuation of the Blue Ridge Mountains into Maryland.

Five hundred Confederates defended the southernmost of the three gaps in South Mountain as the thinly manned line deployed behind a stone wall on the eastern base of Crampton’s Gap. General William Franklin, the VI Corps commander, occupied three hours deploying his forces and the divisions of Major General Slocum and Major General “Baldy” Smith then seized the gap and four hundred prisoners.

At Fox’s Gap, the middle of the three gaps in South Mountain, Major General Jesse Lee Reno, commander of the IX Corps, was killed in action attempting to dislodge the Confederate defenders of D.H. Hills’ Division.

Confederate Brigadier General Samuel Garland,Junior of Major General D.H. Hill’s Division was killed in action defending Fox’s Gap.