Battery AMTB 921

 (1943-1946) - Battery AMTB 921 was a reinforced concrete World War II AMTB rapid fire 90mm gun battery on Fort Varnum, Washington County, Rhode Island. Battery construction started 1 Apr 1943, was completed 2 May 1943 and transferred to the Coast Artillery for use on 22 Jul 1943. Deactivated in 1946.

History
The AMTB battery at Boston Neck consisted of two 90mm M1 guns mounted on 90mm M3 fixed gun mounts and two 90mm M1 guns mounted on 90mm M1A1 mobile gun mounts. The battery had a dual mission of defense against fast enemy motor torpedo boats and enemy aircraft. The effective range of the guns was about 8,000 yards. Each weapon required a crew of 15, 9 men in the gun squad and 6 men in the ammunition squad. Electrical power was furnished by two M-7 Mobile generators.



Current Status
No period guns or mounts in place. Two concrete mounting pads mark the location of the two fixed guns.

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