Great Brewster Island Military Reservation

 (1917-1946) - A World War I Coastal Military Reservation first established in 1917 on Great Brewster Island, Suffolk County, Massachusetts. Named in G.O. 6, 1937. Used during World War II as a mine observation and control station and AMTB gun battery site. Abandoned by the U.S. Army circa 1946.

World War I (1917-1918)
The U.S. Government initially purchased enough land on Great Brewster Island to build a seawall in 1848. The remainder of the island, 21.7 acres in total, was purchased on 18 Aug 1917 during World War I as a searchlight station. The reservation was abandoned after the end of the war.

In 1920, there was some thought given to installing a naval battleship gun turret with two 16" guns on Great Brewster Island Military Reservation but the plan was never implemented. During the 1920s and 1930s, a number of civilian cottages were built on the island without the permission of the U.S. Government, some 24 occupants were noted in 1930. Some cottages can already be seen on the 1919 plan. No harm was being done by these occupants and the government derived some benefit from their presence so the government granted revokable licenses at 5 dollars per year to the occupants. The licenses were probably revoked at the outset of World War II.



World War II (1941-1945)
During World War II, a small post was built on Great Brewster Island Military Reservation to support a mine observation post, a mine casemate and a 90mm gun battery, Battery AMTB 942. The post was built with barracks, a mess hall and a small officers quarters. The mine observation post was a small concrete structure, 13' by 13', equipped with a range finder. The AMTB battery had two fixed 90mm guns, two mobile 90mm guns, two mobile 37mm guns, and an ammunition storage bunker. The AMTB battery was completed in 1943 and the mine observation station was accepted for service 18 May 1944.

The mine casemate was located on the south end of the island and was connected to the minefields by four cable huts. The Great Brewster Island mine casemate was an underground facility used to control up to twenty groups of mines deployed across the main north channel into the harbor. Each mine group contained nineteen underwater mines. Two other mine casemates were located in the Boston Harbor Defense, one at Fort Dawes (10 group capacity) and one at Fort Warren (10 group capacity).

Great Brewster Island Military Reservation was abandoned by the U.S. Army circa 1946 and declared excess by the GSA on 27 Jun 1950. The property was sold to a private owner on 28 Sep 1953 and passed through a number of hands until it was sold to an agency of the State of Massachusetts on 22 Mar 1973.



Current Status
Part of Boston Harbor Islands National Recreation Area and Boston Harbor Islands State Park, Suffolk County, Massachusetts. See Also:
 * Battery AMTB 942

Sources:
 * U.S. Army Corps of Engineers, FUDS Archives Search Report, Findings for the former Great Brewster Island Military Reservation AMTB 942, Project No. D01MA048102, December 1997. Large PDF Download

Links:
 * North American Forts - Brewster Islands Military Reservation
 * Wikipedia - Brewster Islands Military Reservation