The Department of California was one of two Army Departments created September 13, 1858, replacing the original Department of the Pacific and was composed of the territory of the United States lying west of the Rocky Mountains and south of Oregon and Washington territories, except the Rogue River and Umpqua Districts of southwestern Oregon Territory, which were assigned to the Department of California and excluding the Utah Territory east of the 117th meridian west and New Mexico Territory east of the 110th meridian west. Its creation was authorized by General Orders, No. 10, of the War Department, Adjutant-General's Office, September 13, 1858. Headquarters as before remained at San Francisco.