Battery AMTB - Eider Point Spit

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Battery AMTB - Eider Point Spit (1944-Unk) - Battery AMTB - Eider Point Spit was a reinforced concrete World War II AMTB rapid fire 90mm gun battery on Fort Learnard, Aleutians West Census Area, Alaska. Battery construction probably started in 1943, was probably completed and transferred to the Coast Artillery for use in early 1944. Deactivation date is unknown.

Battery AMTB - Eider Point Spit

World War II

Part of the Harbor Defense of Dutch Harbor.

The AMTB battery at Eider Point Spit consisted of two 90mm guns mounted on 90mm M3 fixed gun mounts, two 90mm guns mounted on 90mm M1A1 mobile gun mounts and two 37mm guns mounted on M3 mobile mounts. Four .50 Caliber machine guns on M2 anti-aircraft mounts were authorized and two were emplaced.

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.

The battery was authorized by letter on 17 Feb 1943 and the site was approved on 6 Jul 1943. The armament was allocated by the War Department on 12 Apr 1943.

The Eider Point Spit AMTB battery site was a part of a larger 2,542-acre site that included Battery 298 and the remainder of Fort Learnard. The ATMB Battery was identified as Battery 3a, Location #10a, procured for government use on 30 Apr 1942. The cantonment area for the AMTB personnel was at Location #10b close to the shore at Wide Bay below the AMTB Battery site.

AMTB Battery Cantonment Area.

Concrete pads were provided for both fixed guns and often wooden gun platforms were provided for the mobile guns. Two earth covered concrete magazines provided protection for the ammunition. Electric power was to be provided by M-7 portable generators. An SCR 547-B radar height-finder set was provided to supply slant range or altitude of aircraft.

The Dutch Harbor HD Annex indicates that by 1944 there was a single steel igloo magazine #6, 26' by 30', with a Battle Allowance of 1400 complete rounds and a War Reserve allowance of 1400 complete rounds.

By August 1944 the two mobile guns and ordinance were reported in storage at Fort Mears but the Battery was also listed to be retained for the "Duration of Emergency".

Deactivation date is unknown.

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)

Current Status

No period gun or mounts in place.

Location: Fort Learnard , Aleutians West Census Area, Alaska

Maps & Images

Lat: 53.95925 Long: -166.59125

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

GPS Locations:

See Also:


  • U.S.Army, Supplement to the Harbor Defense Project Harbor Defenses of Dutch Harbor, (SRHDDH), 1944, CDSG
  • Berhow, Mark A. ed, American Seacoast Defenses: A Reference Guide, 3rd Edition - PDF, CDSG ePress, McLean, VA, 2012, ISBN 0-9748167-0-1, page 80-81, 254-256, 224
  • Denfield, Colt, Dutch Harbor Coastal Defenses, Coast Defense Study Group Journal, Volume 7, Number 1, February, 1993, page 30-36.
  • Willford, Glen M., Visitation to Alaskan WWII Coast Defense Sites, August 1997, The CDSG Newsletter, The Coast Defense Study Group, Inc., November 1997, page 2-3.


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