Burns commanded the Philadelphia Brigade for just over a year (October 1861-November 1862), most notably during McClellan's Peninsular Campaign in the spring and summer of 1862. He led the brigade in a pivotal role at the battle of Savage Station (June 29), a rear-guard action fought to protect the Army of the Potomac as it retreated from Richmond. Despite receiving a painful facial wound, Burns and his brigade successfully drove off a Confederate attack and allowed the Union withdrawal to continue without interference. His brigade played another important role in the battle of Glendale on the following day, fending off a Confederate attack that had already routed one Union division, and helping to prevent the strung-out Union army from being cut in half. Perhaps his greatest contribution to history occurred earlier in the campaign; during the battle of Fair Oaks (May 31), Burns had ordered his men to assist an artillery battery that had gotten stuck on a rickety plank bridge over a flooded river. Burns' men helped move the cannon off the bridge and through the mud on the other side, allowing the battery to be in place in time to play a significant role in driving off the last Confederate attack of the day. Even more importantly, a shot fired by that battery severely wounded Confederate General Joseph E. Johnston, who was replaced after the battle by Robert E. Lee.