Civil War actions at Bull Run twice almost brought the military career of Irvin McDowell to an inglorious end. The Ohio native had been raised and educated in France before returning to the United States to attend West Point where he graduated in 1838 and was posted to the artillery. He spent four years as a tactics instructor before serving on John E. Wool's staff during the Mexican War and being brevetted for Buena Vista. During the interwar years he served in the adjutant general's department.

His Civil War-era assignments included: first lieutenant, lst Artillery (since October 7, 1842); brevet major and assistant adjutant general (since March 31, 1856); brigadier general, USA (May 14, 1862); commanding Army and Department of Northeastern Virginia (May 27 - July 25, 1861); commanding Army and Department of Northeastern Virginia, Division of the Potomac July 25 - August 17, 1861); commanding division, Division of the Potomac (October 3, 1861-March 13, 1862); commanding lst Corps, Army of the Potomac (March 13 - April 4, 1862); major general, USV (March 14, 1862); commanding Department of the Rappahannock (April 4 - June 26, 1862); commanding 3rd Corps, Army of Virginia (June 26 - September 5, 1862); and commanding Department of the Pacific (July 1, 1864 - June 27, 1865).

While serving in Washington he became acquainted with Secretary of the Treasury Chase who proved to be instrumental in obtaining his promotion to regular army brigadier and assignment to command of the troops around the capital. Political pressure made it necessary for McDowell to advance on Manassas before his troops were ready. He sent part of his force against Blackburn's Ford along Bull Run and then a few days later made his main attack. While his plan had merit, it was too much for the raw volunteers to accomplish.

Four days after the rout McClellan was placed over McDowell, who a few months later was relegated to the command of a division. When the Army of the Potomac was organized into corps he became head of the 1st Corps which was left behind to guard the approaches to Washington when McClellan moved to the Peninsula. His command was redesignated the Department of the Rappahannock and was supposed to march overland to join McClellan but the activities of Stonewall Jackson in the Shenandoah Valley precluded this.

When John Pope was brought east to command the newly constituted Army of Virginia -- the previously independent commands of McDowell, John C. Fremont, and Nathaniel P. Banks -- McDowell was given a corps. Although his actions at Cedar Mountain earned him the regular army brevet of major general in 1865 -- he already had his second star in the volunteer service -- he was blamed in part for the disaster at 2nd Bull Run. Requesting a court of inquiry, he was eventually cleared of culpability, possibly as a reward for his testimony against Fitz-John Porter. Nonetheless he was not given another combat command and it was not until the last year of the war that he was put in charge of the Pacific Coast.

Mustered out of the volunteers on September 1, 1866, he became a major general in the regular establishment six years later and retired in 1882.