of the Civil War, he was a captain and second in command in the garrison at Fort Sumter, under Major Robert Anderson. He aimed the cannon that fired the first return shot in answer to the Confederate bombardment on April 12, 1861. He subsequently referred to himself as the "hero of Sumter" for this role. Brigade and division command in Virginia Doubleday was promoted to major on May 14, 1861, and commanded the Artillery Department in the Shenandoah Valley from June to August, and then the artillery for Major General Nathaniel Banks's division of the Army of the Potomac. He was appointed brigadier general of volunteers on February 3, 1862, and was assigned to duty in northern Virginia while the Army of the Potomac conducted the Peninsula Campaign. His first combat assignment was to lead the 2nd Brigade, 1st Division, III Corps of the Army of Virginia during the Northern Virginia Campaign. In the actions at Brawner's farm, just before the Second Battle of Bull Run, he took the initiative to send two of his regiments to reinforce Brigadier General John Gibbon's brigade against a larger Confederate force, fighting it to a standstill. (Personal initiative was required since his division commander, Brig. Gen. Rufus King, was incapacitated by an epileptic seizure at the time. He was replaced by Brigadier General John P. Hatch.) His men were routed when they encountered Major General James Longstreet's corps, but by the following day, August 30, he took command of the division when Hatch was wounded, and he led his men to cover the retreat of the Union Army. Doubleday again led the division, now assigned to the I Corps of the Army of the Potomac, after South Mountain, where Hatch was wounded again. At Antietam, he led his men into the deadly fighting in the Cornfield and the West Woods, and one colonel described him as a "gallant officer ... remarkably cool and at the very front of battle." He was wounded when an artillery shell exploded near his horse, throwing him to the ground in a violent fall. He received a brevet promotion to lieutenant colonel in the regular army for his actions at Antietam and was promoted in March 1863 to major general of volunteers, to rank from November 29, 1862. At Fredericksburg in December 1862, his division mostly sat idle. During the winter, the I Corps was reorganized and Doubleday