Battery AMTB 21 - Fort Story

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Battery AMTB 21 - Fort Story (1943-194?) - Battery AMTB 21- Fort Story was a reinforced concrete World War II rapid fire 90mm gun battery on Fort Story, Virginia. AMTB stands for Anti Motor Torpedo Boat. Battery construction started on 25 Sep 1942, was completed on 31 Oct 1942 and transferred to the Coast Artillery for use 2 Aug 1943. Cost at transfer of the gun positions was $ 5,844.80 and the building cost $ 33,622.47. Deactivated in 194?.

Fort Story Battery AMTB 21 Plotting Room, BC station, Magazine and Shell Room Building.
Fort Story Battery AMTB 21 Ammunition Ready Shelter.


Part of the Harbor Defense of Chesapeake Bay.

The AMTB 21 battery at Fort Story consisted of two 90mm gun mounted on 90mm M3 gun mounts. Concrete pads for both these guns were laid in front of the combination plotting room, BC station, magazine and shell room building. 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.

AMTB Front View
AMTB Interior View
AMTB Side View
AMTB Back View

The above photos were taken at Fort Monroe, Battery Parrott

From FM 4-91: "This weapon consists of the 90-mm gun M1 and top carriage M1A1 on the 90-mm gun mount M3. The mount M3 is of the turret type, the shielding being constructed of boiler plates. This boiler plate shield provide fragmentation protection only. No shielding is provided at the rear due to the requirements for service of the piece. A sighting port in the shielding in front permits sighting in direction by the gun pointer."


  • FM 4-91 - 90-MM Gun, Fixed Mount Service of the Piece
  • FM 4-126 - Antiaircraft Artillery, Service of the Piece, 90-mm Antiaircraft Gun
  • TM 9-373 - 90-mm Gun M1 and 90-mm Gun Mount T3 (M3)

Battery AMTB #21 Fort Story Armament (edit list)
Model Serial
Manufacturer Carriage Service
1 90mm Rifle 186.15" M1 6848 General Motors Pedestal Mount, T3, #56, General Motors 1943-1945
2 90mm Rifle 186.15" M1 1423 Wheland Pedestal Mount, T3, #69, General Motors 1943-1945
M 90mm Rifle 186.15" M1 3197 Watervliet Mobile M1A1, #977, AC 1943-1945
M 90mm Rifle 186.15" M1 52 Watervliet Mobile M1A1, #1216, BTDC 1943-1945
Source: RCW Form 1, 15 May 1944, Coast Defense Study Group, Berhow, Mark A. ed, American Seacoast Defenses: A Reference Guide, 2nd Edition, CDSG Press, McLean, VA, 2004, ISBN 0-9748167-0-1, pages 80-81, 210
Battery AMTB #21 Gun Position Plan
Battery AMTB #21 BC Station, Magazine and Shell Room Building

Current Status

No period gun or mounts in place. The gun pads are gone but the ready ammunition shelters remain as does the combination plotting room, BC station, magazine and shell room building. Now used by the Harbor Master.

Location: Fort Story, Virginia.

Maps & Images

Lat: 36.930349 Long: -76.016075



Visited: 21-28 Jul 2010

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