In July 1864, McDowell was given command of the Department of the Pacific. He later commanded the Department of California from July 27, 1865 to March 31, 1868, briefly commanded the Fourth Military Department, then commanded the Department of the East from July 16, 1868 – December 16, 1872. On November 25, 1872, he was promoted to major general. On December 16, 1872, McDowell succeeded General George G. Meade as commander of the Military Division of the South, and remained until June 30, 1876. From July 1, 1876, he was commander of the Division of the Pacific. In 1882, Congress imposed a mandatory retirement age of 64 for military officers, and McDowell retired on October 14 of that year.