The first actual military presence in the Los Angeles area was Spanish Captain Gaspar de Portolá's 1869 land expedition to San Francisco Bay that passed through the area. Under his command were:
The expedition party made camp nine times in what would become Los Angeles County - twice in the San Gabriel Valley in (today's) La Puente and Alhambra, at the Los Angeles River near (today's) Downtown L.A., at the headwaters of Ballona Creek, at (today's) Veteran's Affairs property in Sawtelle, at (today's) Los Encinos State Historic Park, at the site of the future Mission San Fernando Rey de España, near (today's) Six Flags Magic Mountain amusement park, and near another unidentified Indian village north of (today's) Santa Clarita. These were temporary camps, established only for a night or two, but these, in effect, were L.A. County's first military posts.
Soon after, the Spanish missions were established in California, each with a small contingent of soldiers assigned for protection and enforcing the law. Also present across California were a number of military garrisons at presidios (Spanish colonial military forts). The presidios closest to Los Angeles were at San Diego and Santa Barbara. After Mexico won its independence from Spain, the government chose not to garrison any troops in California, except for assigning a few senior military officers assigned to govern as civil authorities. Whatever military requirements came up in the region were handled by locally-organized citizen militias. When U.S. military forces invaded Mexican California in 1846, these militias were the only Mexican forces available to fight back. Considering how out-classed they were by U.S. forces, they offered a good fight, especially the Los Angeles militia, temporarily retaking Los Angeles from American control and twice humbling American forces in the field (see Siege of Los Angeles>, Battle of Dominguez Rancho and Battle of San Pasqual).
In the Los Angeles area, on the U.S. side of the Mexico-U.S. fight over California, was the first U.S. military base in Los Angeles County, temporarily set up at San Pedro harbor in 1846. It was established by U.S. Navy Commodore Robert F. Stockton, who landed there from the U.S. Frigate Congress, with a force of about 250 sailors and marines. Their mission was to capture Los Angeles and bring the region under U.S. control. Although the San Pedro site had commonly been used by visiting merchant vessels, Stockton did not find it an ideal port for naval vessels.
|Fort Moore 1||Los Angeles||U.S. Army||1847||Closed 1848|
|Army Quartermaster Depot, Los Angeles 2||Los Angeles||U.S. Army||Prior to 1861||Closed 1861|
|Camp Fitzgerald 3||Los Angeles||U.S. Army||1861||Closed 1861|
|Camp Lantham 4||Culver City||U.S. Army||1861||Closed 1862|
|Camp Kellogg 5||Culver City||U.S. Army||1862||Closed 1862|
|Drum Barracks 6||Wilmington||U.S. Army||1862||Closed 1871|
|Camp New Carleton 7||Near El Monte||U.S. Army||1862||Closed 1865|
|Fort MacArthur 8||San Pedro||U.S. Army/ Air Force/ Space Force (current)||1914||Active|
|Submarine Base, San Pedro 9||San Pedro||U.S. Navy||1917||Closed 1929|
|San Clemente Island Naval Test Site 10||San Clemente Island||U.S. Navy||1934||Active|
|Edwards Air Force Base 11||Los Angeles & Kern Counties||U.S. Air Force||1938*||Active|
|Naval Air Station San Pedro (Reeves Field) 12||San Pedro (Terminal Island)||U.S. Navy||1938||Closed 1947|
|Long Beach Naval Shipyard 13||Long Beach (Terminal Island)||U.S. Navy||1940||Closed 1997|
|Long Beach Naval Station 14||Long Beach (Terminal Island)||U.S. Navy||1941||Closed 1997|
|Network of U.S. Army Nike Missile Installations||Multiple sites, headquartered at Fort MacArthur in San Pedro.||U.S. Army||1952||Deactivated 1974|
|Naval Hospital, Long Beach 15||Long Beach||U.S. Navy||1967||Closed 1994|
|Los Angeles Air Force Base 16||El Segundo||U.S. Air Force/ Space Force (current)||1962||Active|
* Expanded from Kern County into Los Angeles County during 1940s.
(1) First established as a rudimentary fortification in 1846 by U.S. Marines and Californian volunteers trying to fend off Mexican resistance. Later a permanent fortification constructed by the 1st U.S. Dragoons and the Morman Battalion. Site of first American Independence Day celebration in California on July 4, 1847. Construction was never completed. Named for U.S. Army Captain Benjamin D. Moore, who was killed on December 6, 1846, with 21 other Americans at the Battle of San Pasqual in San Diego County.
(2) Served simply as a storage facility for a stock of military arms, ammunition and supplies. It was manned by a single army officer. At the start of the American Civil War, the stocks were turned over to army forces deployed into the area.
(3) A temporary series of camps established by the 1st Regiment of U.S. Dragoons upon deployment into the Los Angeles at the start of the American Civil War to quell local secessionist actions. Named for Brevet Major Edward H. Fitzgerald, 1st U.S. Dragoons, who died in 1860.
(4) Army camp established to more permanently garrison the 1st Regiment of U.S. Dragoons and 4th California Infantry Regiment (volunteers). First headquarters for U.S. Army in Southern California and the Territory of Arizona. Named for U.S. Senator Milton S. Latham and former California governor.
(5) Army camp established to garrison the 5th California Infantry Regiment (volunteers). Named for Colonel John Kellogg, regimental commander.
(6) Headquarters of U.S. Army in Southern California and the Territory of Arizona during the American Civil War. At peak, garrisoned 7,000 troops as a Union military presence amidst significant Confederacy sympathies in California. Named for Lt. Col. Richard Coulter Drum, Adjutant General of the Department of the Pacific in San Francisco.
(7) Army camp established to garrison 1st California Cavalry re-deployed from San Bernandino due to flooding at "Old" Camp Carleton. Troops there policed pro-Confederacy activities in Easter Los Angeles County and San Bernardino County. Named for Major James Henry Carleton, 1st U.S. Dragoons.
(8) Established as an Army mustering and training center during World War I and later for coastal defense artillery, followed by anti-aircraft missile units. In 1982, what had had not been turned over to the City of Los Angeles was transferred to the U.S. Air Force for administration and housing, primarily for personnel from the Los Angeles Air Force Base. In 2021, upon the transfer of control of Los Angeles Air Force Base from the Air Force to the U.S. Space Force, the facility likewise came under the control of the Space Force. The installation was named for Spanish-American War commander Lt. General Arthur MacArthur, father of WWII General of the Army Douglas MacArthur.
(9) After submarines and tenders had operated from temporary facilities at San Pedro wharfs since 1913, a permanent base was established in 1917 as the first U.S. submarine base on the West Coast, complete with a submarine training school. Surface ships also operated from the base during the 1920s.
(10) Established for ship-to-shore artillery training and later, during World War II, for amphibious landing training. Currently includes live-fire and missile test ranges, an auxiliary naval airfield and Navy SEAL training facilities.
(11) Established as a bombing range and later as a test and research center for high-performance aircraft. Also served as the landing site for NASA space shuttles. First named Muroc Air Force Base, it was later renamed for U.S. Air Force Captain Glen W. Edwards, killed when a YB-49 "Flying Wing" he piloted crashed on June 5, 1948.
(12) Served as an air facility for retrofitting naval surveillance aircraft and aerial coastal patrol.
(13) Served as dry docks for overhaul and maintenance of naval surface vessels. Featured "Herman the German," transferred to Long Beach after capture from Germany in War World War II and one of the largest floating cranes during much of its time.
(14) Adjacent to the Naval Shipyard and originally named Roosevelt Base (for President Franklin D. Roosevelt), it served as a logistical and home base for naval vessels (including the battleships). Housing complexes for military families were also operated in Palos Verdes and San Pedro.
(15) Served as a key medical center for personnel medically evacuated from the Pacific.
(16) Headquarters of Space Systems Command of the U.S. Space Force. The base had previously under U.S. Air Force command until 2021 when its operations were then transferred over to the U.S. Space Force.
As part of a U.S. Army experiment in the use of camels in the late 1850s, 31 camels ended up for service at Fort Tejon in Kern County. The experiment was effectively ended at the start of the U.S. civil war. In 1861, the animals were turned over to Army Captain Hancock at the Los Angeles Quartermaster Depot in Los Angeles. There is no further record of what happened to them. Thus ended the U.S. Army Camel Corps.