South Mountain: A Much-Needed Morale Booster for the Army of the Potomac

During an interview with other Antietam historians as part of an upcoming ECW podcast (stay tuned), Chris Mackowski asked the panel: “Was the battle of South Mountain where the Maryland Campaign was won or lost?” I replied, “No,” but explained South Mountain’s importance for the campaign, particularly regarding the boost it provided for the Army of the Potomac’s morale.

To put it bluntly, the army’s morale was poor following Second Bull Run. Lieutenant Colonel Adinoram Warner, 10th Pennsylvania Reserve Infantry, summed up that defeat’s impact on his men during the Battle of South Mountain: “I moved my Reg. forward and soon received a shower of bullets from across the revine partly on our front. We opened fire, part of the men moving rapidly up under cover and firing evenly on the rebels as they showed themselves among the rocks, and a part hanging back in a way they had never done before. I saw they hesitated to enter the revine, but unsurely faltered just in the place where they were most exposed. This was the effect of the defeat at Bull Run.”

When the battle smoke cleared, and the sun rose the next morning, the men of the Army of the Potomac realized they held the battlefield. General George McClellan told General-in-Chief Henry Halleck, “The morale of our men is now restored.”

Soldiers’ accounts support McClellan’s statement. The victory at South Mountain lifted a heavy weight off the shoulders of the army. “The espirit de corps of this fine body of troops was now particularly high,” said Pvt. George Kimball, 12th Massachusetts Infantry. “The men felt that if any shadow of discredit had attached to them on account of the disaster at Manassas, it had been swept away by the brilliant flank movement at South Mountain.”

As for Warner, he found a large tree to sleep beneath and reflected on the hard work of September 14. “We had been baffled on the Peninsula; had been beaten and discomfited at Bull Run; the enemy were invading the North; all looked gloomy yet I did not know that I had been dispirited but the change was so glorious! The consciousness that we had by sheer hard fighting, beaten the enemy and driven him from his strong positions filled me to overflowing and gave me confidence that we would finally win and the country be safe.” That was quite the turnaround from where his men were mentally hours earlier, where the defeat at Bull Run made them falter.

The September 14, 1862, battle of South Mountain paved the way for the Army of the Potomac to fight another tough, bloody battle three days later along Antietam Creek.