Camp Lockett was a United States Army military post in Campo, California, east of San Diego, and north of the Mexican border. Camp Lockett has historical connections to the Buffalo Soldiers due to the 10th and 28th Cavalry Regiments having been garrisoned there during World War II. It was named in honor of Colonel James R. Lockett who fought in the Spanish–American War, Philippine Insurrection, and the Punitive Expedition. There was an active preservation effort underway with long-term plans of creating the 'Camp Locket Historic District' in the National Register of Historic Places, which ended due to private property concerns. In 2009 it was designated as a California Historical Landmark, and there are plans to create a county park out of the majority of its former area.

Although travel through the area had been occurring for centuries, with the Diegueño Native Americans having lived there long before European settlement, it wasn't until the end of the 1860s and the early 1870s when a permanent Non-Native American settlement was established in the Campo Valley area. The area was settled by people migrating west from Texas, so much so that the area at one time was called "Little Texas". In 1869, John Capron established a regular stagecoach run from San Diego, by way of Dulzura and Campo, to Yuma which continued to run until 1912.

As in many places in the American Southwest, this immigration brought new interactions between the people living in the area, including the Mexicans who lived not too far to the south. A telegraph line and a stop for the stagecoach were established, and run by the Larkin family. This brought additional commerce to the area; however, with commerce came crime. On December 4, 1875, a gunfight between the citizens of Campo and a group of Mexican bandits, who had earlier killed the former Governor of Baja California Antonio Sosa in a robbery, took place at Gaskill Brothers' Stone Store. After all was said and done the events of that day led to eight dead and two wounded. Company G of the 1st Cavalry Regiment was sent by order of Major General John Schofield to San Diego to provide armed assistance to the area. Lieutenant Storey commanded a detachment of ten troopers, detaching four troopers to conduct "outpost" duty after shooting himself in the hip, thus providing the first soldiers to be stationed in what would be Camp Lockett.

In May 1876, a large assembly of outlaws assembled in Tecate to attempt to rob the stagecoach station. The company was sent east to assist under the command of Captain Reuben F. Bernard, a veteran of the Modoc War; this dispersed the would-be assailants. In the summer of that same year, a group of Native Americans came north from Mexico and began living off the Larkin Family's cattle. Contacting the Alcalde (mayor) of Tecate, Pete Larkin was advised to confront the Native Americans. The confrontation became a fight, leading to the death of a Native American. This brought reprisal when the chief of the Native Americans asked for protection from the Alcalde, who subsequently assembled a posse and drove the cattle south of the border. Again the Cavalry came east to assist, which led to the abandoning of the cattle by the posse of the Alcalde and the posse's dispersal. This led the increase to the size of those on "outpost" duty to that of a squad.

By 1877 the squad's duty ended as the 1st Cavalry Regiment was sent north due to the Little Big Horn Campaign, being replaced in San Diego by H Company, 8th Infantry Regiment. Company H was later replaced by Company I of the same Infantry Regiment in 1878 due to the Bannock Campaign. They would remain in San Diego until at least 1898, however no significant military presence would be seen Campo until 1895. In that year, about forty Yaquis were pressed into the Mexican Army, and later mutinied in Ensenada; in doing so they killed three people including their Captain's wife, and began to flee northward to obtain horses to travel back to where they came from. In response the U.S. Army sent ten infantrymen under the command of Lieutenant Hubert to Campo. Although a farm was raided, the infantry's presence prevented the group from continuing further into the United States, and they were eventually subdued by Mexican Militia forces south of Jacumba.

In response to the Zimmermann Telegram it was decided that detachments of the 11th Cavalry Regiment would be stationed along the US–Mexico border. In part this was done by stationing Troop E at what would become Camp Lockett in 1918, named after the 4th Colonel in command of the 11th Cavalry Regiment. Troop E would remain stationed there until August 1920 when they were relocated to the Presidio of Monterey, and replaced by Troop D of the same regiment. Later on in that same year the force at Campo would be reduced to that of a platoon, while the rest of the Troop moved to Camp Lawrence J. Hearn at Palm City, near present-day Imperial Beach. Eventually both locations would be abandoned when the Regiment was recombined in Monterey in the 1920s.

The first phase of construction, which occurred in 1941, housed the 11th Cavalry Regiment. Standard Army Quartermaster Corps Series 700 and 800 plans were used for the original camp and included housing areas (barracks, officers quarters, day room, mess hall, and storehouse), stable areas (stables, blacksmith shops, and hay sheds), a veterinary facility, the quartermaster area, motor pool area, hospital (staff quarters and wards), administration buildings, recreation buildings, a chapel, and post exchange.

Original infrastructure included roads and streets, a sewage treatment plant, incinerator, and water supply system. Importantly, during this time several buildings from the pre-Army era were converted to military support uses, including the 1885 Gaskill Stone Store. By November 1941, Camp Lockett housing was ready for occupancy. It was the last base built for California in the nation. Along with thousands of Soldiers and horses, there lived a track supervisor for the San Diego and Arizona Eastern Railway lived on the base, which encircled its Campo Depot.