Major-General Irvin McDowell was born in Columbus, Ohio on 15 October 1818. He was rendered distinguished service in the Mexican War. In 1841 he served at West Point as assistant instructor in tactics, becoming adjutant in 1845.

As brigadier-general at the head of the Department of Northeastern Virginia, he had command of the Union army at First Bull Run. Afterward, with a commission of major-general of volunteers, he had a division in the Army of the Potomac. in further reorganizations and changes, he headed his troops a commander of the First Corps, Army of the Potomac, Department of the Rappahannock, and the Third Crops, Army of Virginia.

His conspicuous services at Cedar Mountain won him the brevet of major-general, which full rank he attained in 1872. McDowell was blamed for the subsequent disaster at Second Bull Run. He escaped culpability by testifying against Maj. Gen. Fitz John Porter, whom Pope court-martialed for alleged insubordination in that battle. Despite his formal escape, McDowell spent the following two years in effective exile from the leadership of the Army. He was relieved from field service and was president of several army boards.

In July 1864, he was placed at the head of the Department of the Pacific, and after the war held various commands. He commanded the Department of California, the Fourth Military District (the military government for Arkansas and Louisiana during Reconstruction), and the Department of the West.

McDowell retired in 1882 after serving as park commissioner for San Francisco, where he died on 4 May 1885. He is buried in San Francisco National Cemetery in the Presidio of San Francisco.