Situated almost directly between Fort Stark and Fort Constitution on New Castle Island is the military reservation that would eventually become Camp Langdon. The original land was purchased in 1909 to handle the overflow of soldiers in the surrounding forts that there was no room for and it was called the Reservation for the Artillery Post. It was used for living quarters and for training.
At the beginning of WWI in 1918 an AA Battery, which was never assigned an official battery number, was built consisting of two 3" fixed M1917 AA guns on concrete pads. Their fire was controlled by both Fort Stark and Fort Constitution. The guns were removed around 1930 and sent to an unknown location and AA Battery 1 was never fortified for WWII. Both pads are still visible today. Gun 2 has been modified though. In 1921 a 36" GE trailer mounted searchlight (position 4) was installed. The searchlight was removed in 1925.
In 1937 the reservation was renamed New Castle Military Reservation and a mobile AA pad was built. The pad was never fortified though. On November 23, 1940 twenty eight new buildings were started on bringing the reservation up to 20 barracks, 7 mess halls, a day building, a 50 bed hospital, officer's quarters, motor pool, chapel, fire station, headquarters and a theater, just to name some, and a concrete pier. On April 14, 1941 the reservation was renamed to Camp Langdon after Governor John Langdon. A military perimeter consisting of a 6 foot high chain link fence with 1 foot barbed wire extensions was erected around the reservation. A 60" Sperry searchlight (position 10) was installed on a steel tower and the reservation was named Headquarters for Harbor Defenses.
In 1948 the Army transferred the reservation to the Navy and it was renamed the Camp Langdon Annex. In 1961 a portion was transferred to the Marines. In 1963 the land was transferred to the Town of New Castle for use as a park.