John L Burns was of Scottish ancestry; his father claimed a relationship with poet Robert Burns. He served as an enlisted man in the War of 1812, and volunteered for both the Mexican-American War and the Civil War. He was rejected for combat duty in the latter war due to his advanced age, but he served as a teamster in support of the Union Army
On the first day of the Battle of Gettysburg, July 1, 1863, Burns took up his flintlock musket and powder horn and walked out to the scene of the fighting. He encountered a wounded Union soldier and asked if he could use his more modern rifle; the soldier agreed and Burns moved on with the rifle and with cartridges in his pocket.In McPherson (Herbst) Woods, Burns fought with the 7th Wisconsin Infantry and then moved to join the 24th Michigan near the eastern end of the woods.He served as a sharpshooter, in one case shooting a charging Confederate officer from his horse. As the Union line began to give way, Burns received wounds in the arm, the leg, and several minor ones in the breast; the Union soldiers were forced to leave him behind on the field.Injured and exhausted, the old man was able to crawl away from his rifle and to hastily bury his ammunition. He convinced the Confederates that he was a noncombatant.