When he returned from
Utah in 1859, Reno was promoted to captain after fourteen years of continuous service in the Army. Captain Reno then took command of the
Mount Vernon Arsenal near
Mount Vernon, Alabama, in 1859. At dawn on January 4, 1861, Reno was forced to surrender the arsenal to troops from
Alabama, a bloodless transfer ordered by the governor of Alabama,
Andrew B. Moore. Alabama seceded from the
Union a week later. Upon leaving Alabama with his small force, Reno was temporarily assigned to command the
Fort Leavenworth Arsenal until he was appointed
brigadier general of volunteers in the fall of 1861. He transferred to
Virginia, took command of the 2nd Brigade,
Burnside Expeditionary Force, and soon had organized five regiments. The 2nd Brigade fought in
Major General Ambrose Burnside's
North Carolina Expedition from February through July 1862. Reno became a division commander in the IX Corps, which had become part of the
Army of the Potomac. In the
Northern Virginia Campaign, Reno actively opposed his friend and classmate
Stonewall Jackson during the
Second Battle of Bull Run and the
Battle of Chantilly. Reno was appointed a
major general on August 20, 1862. (This promotion was confirmed posthumously on March 9, 1863, with date of rank established as July 18, 1862.) Burnside became commander of the Army of the Potomac's right wing for the start of the
Maryland Campaign in September, elevating Reno to command of the IX Corps from September 3. Reno had a reputation as a "soldier's soldier" and often was right beside his troops without a sword or any sign of rank. On September 12, 1862, Reno's IX Corps spent the day in
Frederick, Maryland, as the
Army of the Potomac under Major General
George McClellan advanced westward in pursuit of the Confederate
Army of Northern Virginia under Gen.
Robert E. Lee. Elements of Lee's army defended three low-lying "gaps" of
South Mountain—
Crampton's,
Turner's, and
Fox's—while concentrating at
Sharpsburg, Maryland, to the west, the location of the subsequent
Battle of Antietam (September 17, 1862). In the
Battle of South Mountain on September 14, Reno stopped directly in front of his troops as he reconnoitered the enemy's forces advancing up the road at Fox's Gap. He was shot in the chest by a rookie Union soldier from the 35th Massachusetts who mistook him for Confederate cavalry at dusk. The manuscript of Union Officer
Ezra A. Carman, published in The Maryland Campaign of September 1862, Volume 1: South Mountain, Edited and annotated by Thomas G. Clemens, documents Reno's death by men of General
John Bell Hood who were in the treeline and fired from the woods that the 35th Massachusetts skirmishers had just retreated from. He was brought by stretcher to Brigadier General
Samuel D. Sturgis's command post and said in a clear voice, "Hallo, Sam, I'm dead!" Sturgis, a long-time acquaintance and fellow member of the
West Point Class of 1846, thought that he sounded so natural that he must be joking and told Reno that he hoped it was not as bad as all that. Reno repeated, "Yes, yes, I'm dead—good-by!", dying a few minutes later. In his official report, Confederate general
Daniel Harvey Hill sarcastically remarked, "The Yankees on their side lost General Reno, a renegade Virginian, who was killed by a happy shot from the Twenty-third North Carolina." ==Legacy==