In 1861, McDowell was promoted to brigadier general and assigned commander of the newly organized army at Washington. In the First Battle of Manassas, he was forced to advance before his army was ready, and as a result, his army was defeated. McDowell took the blame, and he was relieved of army command. In March 1862, he was appointed commander of a division, and promoted to major general of volunteers and assigned command of the I Corps of the Army of the Army Potomac. Soon, officials in Washington redesignated his division the Army of the Rappahannock, and put him in charge of the defense of Washington. McDowell'³ command was later redesignated the III Corps of the Army of Virginia. In 1862, at the Battle of First Manassas, the Army of Virginia was defeated and fell back into the defenses of Washington. Again, McDowell took the blame, and he was relieved of his command. He held no further field command during the war. He was put in charge of the Department of the Pacific, and taken of the war, thus, after commanding various military departments, McDowell retired from the service in 1882.