Battery AMTB - Cabrillo

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Battery AMTB - Cabrillo (1943-1946) - Battery AMTB - Cabrillo was a World War II, rapid fire, 90mm gun battery on Fort Rosecrans, San Diego County, California. Battery construction started 29 Jun 1943, was completed 26 Aug 1943 and transferred to the Coast Artillery for use 14 Dec 1943. Deactivated in 1946.

World War II

Part of the Harbor Defense of San Diego.

The AMTB battery at Point Loma consisted of two 90mm guns mounted on 90mm M3 fixed gun mounts and two 90mm guns mounted on 90mm M1A1 mobile gun mounts. Concrete pads were provided for both fixed guns and wooden gun platforms were provided for the mobile guns. The mobile guns were not normally emplaced. Two earth covered concrete magazines provided protection for the ammunition. Electric power was provided by M-7 portable generators.

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 or 4.5 miles. 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 - Cabrillo Armament (edit list)
Model Serial
Manufacturer Carriage Service
1 90mm Rifle 186.15" M1 5455 Watervliet Pedestal Mount, M3, #T3-201, Fisher 1943-1946
2 90mm Rifle 186.15" M1 1333 Wheland Pedestal Mount, M3, #T3-92, Fisher 1943-1946
1. RCW Form 1, 12 Apr 1944
3. 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, 217.
4. Report of Rounds Fired from Seacoast Artillery Guns, HD Commander, 17 Jan 1946, NARA RG165, E257 Box 68 - Bolling Smith.
Battery AMTB - Cabrillo Plan

Current Status

Part of the Cabrillo National Monument, San Diego County, California. Battery destroyed, no period gun or mounts in place.

Location: Cabrillo National Monument, San Diego County, California. Map point is approximate.

Maps & Images

Lat: 32.667676 Long: -117.243798

  • Multi Maps from ACME
  • Maps from Bing
  • Maps from Google
  • Elevation: 39.9'


  • U.S.Army, Supplement to the Harbor Defense Project of San Diego, (HDSD-AN-45), 1 Jul 1945, CDSG


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