District of Southern California

The District of Southern California was a district of a new department of the United States Army called Department of the Pacific.

The department was created on January 15, 1861, during the American Civil War. The District of Southern California was established on September 25, 1861. By 1863, the department had five districts, including the District of Southern California. The district was composed of San Luis Obispo County, Tulare County, Santa Barbara County, Los Angeles County, San Bernardino County, and San Diego County. Its first headquarters was located at Camp Latham, located west of Los Angeles. The headquarters was later moved to Drum Barracks.

On July 27, 1865, the Military Division of the Pacific was created under Major General Henry W. Halleck, replacing the Department of the Pacific. The department consisted of the Department of the Columbia and the expanded Department of California absorbing the District of Southern California that now consisted of the States of California and Nevada and the Territory of New Mexico and Territory of Arizona.