Fort Detrick is a U.S. Army installation of about 1,200 acres in Frederick, Maryland. Its major tenant is the U.S. Army Medical Research and Development Command, and it also houses the Army's biodefense laboratory, USAMRIID, the National Cancer Institute's Frederick campus, the National Biodefense Analysis and Countermeasures Center and the National Center for Medical Intelligence. The garrison says it supports five cabinet-level departments.

The site began as a municipal airfield in 1929 and is named for Major Frederick L. Detrick, a World War I flight surgeon. In March 1943 the Army bought it, renamed it Camp Detrick and opened its Biological Warfare Laboratories there; it became Fort Detrick in 1956. The post was the center of the U.S. offensive biological weapons program until President Richard Nixon renounced offensive biological research on November 25, 1969. In the 1950s it ran Operation Whitecoat, a program of medical studies on volunteers, and a 1977 Senate hearing on the CIA's MKULTRA program took up related biological-agent work at the post. In 2019 federal inspectors halted USAMRIID's high-containment work for several months after finding containment breaches.

The post's place in UFO debate rests on claims about non-human biologics rather than sightings. In a passage from his 2024 memoir Imminent, shared widely in March 2026, Lue Elizondo wrote that he had learned non-human biological samples "had moved many times," with some at Fort Detrick or with the Food and Drug Administration. An anonymous Reddit user who claimed in 2023 to have studied "Exo-Biospheric-Organisms" for a national security contractor placed that work in a restricted basement of a Fort Detrick laboratory; the claims remain unverified. After physicist Eric Davis said in August 2026 that recovered bodies had been taken to the Armed Forces Institute of Pathology, online researchers tied his account to Fort Detrick, although that institute was based at Walter Reed Army Medical Center in Washington.

Fort Detrick's documented history explains why it recurs in these accounts. For eight decades it has been the Army's main center for work on dangerous pathogens, first for offensive weapons and since 1969 for defense, with a record of secrecy later examined by the Senate. That made it a frequent answer in disclosure debates to the question of where biological material might be studied, a role built on testimony and secondhand accounts, since no released government record places non-human remains or samples at the installation.