The Battle of South Mountain - 157 Years Ago Today

On this date in 1862, the Army of Northern Virginia clashed with the Army of the Potomac at three separate gaps in the South Mountain range in Maryland.

Bolstered by an intercepted copy of Lee's operational plans, George McClellan marched his 80,000-strong Army of the Potomac out of the capital defenses with uncharacteristic speed. Lee's army was divided and vulnerable to defeat in detail. The only thing standing between the Army of the Potomac and a divided Confederate army was South Mountain. If McClellan could get through to the other side, Lee's forces would be in real danger of annihilation.

And so, on September 14, 1862, McClellan's army smashed into the mountain passes that led into the valley beyond. Crampton's Gap, Fox's Gap, and Turner's Gap became whirlwinds of death as both sides fought desperately to gain possession of these strategic byways.

In the end, Lee's outnumbered forces were forced to retreat but had managed to buy Lee enough time to get his army away from South Mountain and to a more defensible position around a small German farm town called Sharpsburg. There Lee took defense behind a tributary of the Potomac - a creek known to locals as Antietam.

The Battle of South Mountain cost the Union army some 2,300 casualties while the Confederates suffered nearly 2,700 men killed and wounded. It was all a prelude to what would become the bloodiest single day in American history.