Battery AMTB - Fort Sumter

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Battery AMTB - Fort Sumter (1943-1946) - Battery AMTB - Fort Sumter was a World War II rapid fire 90mm gun battery on Fort Sumter, Charleston County, South Carolina. AMTB stands for Anti Motor Torpedo Boat. Battery construction started 12 Feb 1943, was completed 3 Apr 1943 and transferred to the Coast Artillery for use 2 Jul 1943 at a cost of $ 13,470.53. Deactivated in 1946.

Approximate location of Gun #3 of the AMTB Battery

World War II (1941-1945)

Part of the Harbor Defense of Charleston.

The AMTB battery at Fort Sumter consisted of two 90mm M1 guns mounted on 90mm M3 fixed gun mounts and two 90mm M1 guns mounted on M1A1 mobile mounts. The mobile guns remained in storage until required. Concrete pads for both fixed guns were laid on the southeast parapet of the old fort. 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 - Fort Sumter Armament (edit list)
Model Serial
Manufacturer Carriage Service
1 90mm Rifle 186.15" M1 6854 General Motors Pedestal Mount, M3, #54, General Motors 1943-1946
2 90mm Rifle 186.15" M1 6919 General Motors Pedestal Mount, M3, #108, General Motors 1943-1946
M 90mm Rifle 186.15" M1 540 Wellman Mobile M1A1 #5991, Wellman 1943-1946 Note 1
M 90mm Rifle 186.15" M1 550 Wellman Mobile M1A1 #6004, Wellman 1943-1946 Note 1
Source: RCW Form 1, 15 Jun 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
Note 1: One of four mobile gun/carriage sets kept in ordnance storage for use in the four mobile gun positions
Battery AMTB - Fort Sumter Plan

Current Status

No period gun or mounts in place.

Location: Fort Sumter, Charleston County, South Carolina. Gun emplacement map points are approximate.

Maps & Images

Lat: 32.7523573 Long: -79.8746663


  • U.S.Army, Supplement to the Harbor Defense Project of Charleston, S.C., (HDCN-AN-45), 15 Mar 1945, CDSG


Visited: 23 Jan 2010

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