John Coughlin’s military legacy is defined by a singular moment of decisive initiative during the American Civil War. Serving with the 10th New Hampshire Infantry, Coughlin found himself in the thick of the Bermuda Hundred Campaign in Virginia. On the night of May 9, 1864, near Swift Creek, his brigade fell under a sudden and heavy Confederate assault.

The darkness and the unexpected nature of the attack caused immediate chaos within the Union lines. As Burnham’s Brigade began to fracture and fall into confusion, the risk of a total rout was imminent. Specifically at risk was Hunt’s Battery; without infantry protection, the Union artillery pieces were certain to be captured or destroyed by the advancing enemy.

Without waiting for formal orders from his superiors, Lieutenant Colonel Coughlin took command of the situation. He maneuvered the 10th New Hampshire forward through the confusion, positioning his men directly between the charging Confederate forces and the vulnerable artillery battery. By interposing his regiment as a human shield and a firing line, he checked the enemy’s momentum.

Coughlin’s rapid response successfully repulsed the night attack. His actions not only stabilized the brigade’s position but directly prevented the loss of the guns at Hunt’s Battery. For this act of gallantry and “distinguished gallantry in action,” Coughlin was later recognized with the nation’s highest military honor.