Construction began on 1 May 1941 under Lieutenant Colonel William P.T. Hill, on 11,000 acres of Onslow County farmland the federal government had just acquired. About 2,400 residents were displaced. The first base headquarters was set up in a summer cottage on Montford Point and moved to Hadnot Point in 1942. The place was simply called Marine Barracks New River. Then in November 1942 John A. Lejeune died. Lejeune, the 13th Commandant of the Marine Corps and the man who had shaped the modern Corps in the 1920s, had become a Marine legend. The base was renamed Camp Lejeune in his honor. It has carried the name for eighty-three years.

After President Roosevelt signed Executive Order 8802 in 1941 desegregating defense industries, the Marine Corps reluctantly began recruiting African American Marines. Between 1942 and 1949, about 20,000 of them trained at Montford Point, a segregated satellite camp on the western side of the base. They were called Montford Point Marines, and they earned a reputation in the Pacific and in Korea that finally overcame the institutional resistance to their presence. After Truman ordered the armed forces fully integrated in 1948, Montford Point was closed and renamed Camp Gilbert H. Johnson, after one of the most respected Montford Point drill instructors. Today the Montford Point Marine Association keeps their memory active. In 2012 the surviving Montford Point Marines were collectively awarded the Congressional Gold Medal.

From 1953 to 1987 the wells supplying Tarawa Terrace, Hadnot Point, and other base housing areas drew water tainted with industrial solvents. Tarawa Terrace was contaminated mostly by perchloroethylene from an off-base dry cleaner; Hadnot Point was contaminated by trichloroethylene used as a degreaser and by benzene from underground fuel leaks. The wells were not shut down until the mid-1980s. The Marines and their families who lived and worked there drank, bathed, washed dishes, and made baby formula with the water. The list of associated conditions is grim: leukemia, multiple myeloma, non-Hodgkin's lymphoma, breast cancer, esophageal cancer, kidney cancer, bladder cancer, miscarriages, birth defects, scleroderma, Parkinson's disease. A 2023 cohort study found that veterans stationed at Lejeune had Parkinson's rates 70 percent higher than veterans stationed at Camp Pendleton. ATSDR's Cancer Incidence Study, released in early 2024 after eight years of work, confirmed elevated risk of multiple cancers.

The 2012 Janey Ensminger Act, named for Jerry Ensminger's daughter, authorized VA medical care for up to 750,000 Marines and family members who had lived on base between 1957 and 1987 and developed any of fifteen listed conditions. But the law required residence on base, excluding dependents whose families slept off base even if they spent every day at Camp Lejeune. In August 2022 President Biden signed the Camp Lejeune Justice Act as part of the PACT Act, finally allowing victims to sue for compensation and removing the on-base sleeping requirement. By the August 2024 deadline, the Navy had received over 546,500 claims. Jerry Ensminger is still alive. He is still answering phone calls from families just learning what happened to their loved ones. He is the reason any of this exists in law.

Camp Lejeune (KNJM) sits at 34.59 degrees north, 77.34 degrees west, sprawling across 246 square miles of coastal Onslow County. View from 3,000 to 5,000 feet AGL to see the New River, the fourteen miles of Atlantic beach used for amphibious training, and the broader installation footprint. Restricted airspace covers most of the base; coordinate with Lejeune approach. Nearest civil alternate is Albert J. Ellis Airport (KOAJ) about fifteen nautical miles northwest. MCAS New River (KNCA) is a few miles north. Coastal weather changes quickly; summer thunderstorms are common.