Department of the Pacific

The department reported directly to the headquarters of the Army in Washington, D.C.

The Department of California included the territory west of the Rockies, the Umpqua and Rogue River districts in Oregon, Utah and New Mexico.

The first commander of the new Department of the Pacific was Colonel (Brevet Brigadier General) Albert Sidney Johnston who was later to become a prominent General in the Confederate Army.

[11] The Department of the Pacific had six subordinate military districts during the Civil War: On June 27, 1865, the Military Division of the Pacific was created under Major General Henry W. Halleck, replacing the Department of the Pacific, consisting of the Department of the Columbia that now consisted of the state of Oregon and the territories of Washington and Idaho and the expanded Department of California that now consisted of the states of California and Nevada and the Territory of New Mexico and Territory of Arizona.

[12] On 30 May 1898, Gen. Wesley Merritt established in San Francisco the Headquarters, US Expeditionary Forces and Department of the Pacific for the campaign to support Adm. Dewey's forces in the Philippines during the Spanish–American War.