Historic California Posts, Camps, Stations and Airfields
Fort MacArthur: Anti-Motor Torpedo Boat Battery Gaffey Bulge
90mm gun on an M3 fixed mount (Coast Defense Study Group)
Anti-Motor Torpedo Boat Batteries, Harbor Defenses of Los Angeles
by Justin M. Ruhge

In 1942 five batteries of AMTB guns protected the San Pedro Harbor. There were four batteries of 90-mm guns and 37-mm guns and one of only 37-mm guns. These were fast-firing weapons, which were supplemented with 50-caliber machine guns and searchlights as needed. The 90-mm batteries were four guns, two of which were permanent and two mobile. These were supplemented with two mobile 37-mm guns.

These batteries were located at the Gaffey Bulge where Gaffey Street winds around Battery Leary-Merriam; JAAN No. 1, Navy Field; JAAN No. 2, Bluff Park; and Terminal Island.

The fifth battery was designated Dolphins. This was a line of 10 37-mm guns on towers with searchlights located along the harbor breakwater - making a total of 34 guns.

AMTB Gaffey Bulge was armed with two fixed 90mm guns on M3 fixed mounts and two on M1 mobile mounts.

Location of Anti-Motor Torpedo Boat Batteries, July 1944. Click to view a larger image (Coast Defense Study Group)
Location of Anti-Motor Torpedo Boat Searchlights, July 1944. Click to view a larger image (Coast Defense Study Group)
Report of Complete Works - Seacost Fortifications
Source: Coast Defense Studty Group
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Fort MacArthur Museum
Wikipedia: M1/M2/M3 90mm Gun
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Updated 23 June 2017