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U.S. Seacoast Defense 1781-1950: A Brief History

The World War II Era, 1940-1950

Rearming the American coastline with long-range 16-inch weapons from existing army and navy stocks finally got started in earnest in the late 1930s. These guns were installed in emplacements with substantial overhead protection. Two casemated 16-inch batteries were constructed at San Francisco from 1937 to 1940, and a few other batteries were started soon after. A full construction program was authorized by Congress in September of 1940. The program planned for new defenses at some 19 harbors along both coasts. The fortifications were built using two standardized designs, a two-gun 16-inch battery (or in some cases remodeled 12-inch batteries) and a two-gun 6-inch battery, along with their supporting command and observing stations. When America entered the war in December of 1941, a large number of mobile weapons were rushed to both coasts. A number of other “temporary” seacoast defenses were built using old naval weapons and relocated army seacoast weapons.

The first post-seacoast artillery American continental defense system was the Nike surface to air missile (1954-1974). (Site SF-88, Golden Gate National Recreation Area, Marin Headlands, CA)

The first post-seacoast artillery American continental defense system was the Nike surface to air missile (1954-1974).
(Site SF-88, Golden Gate National Recreation Area, Marin Headlands, CA)

The seacoast defense construction program went into high gear in 1942, with priority for the Pacific Coast. New 90 mm guns were added to the program as anti-motor torpedo boat (AMTB) batteries. By that year permanent defenses were planned for 33 harbor areas. However, the possibility of a Japanese attack on the American mainland diminished, and the need for offensive weapons and manpower increased. As a result, the construction program was repeatedly curtailed, and halted altogether by 1948.

After the war, the lack of any blue-water naval threat sealed the death warrant for the coast artillery, supplemented by new amphibious landing techniques that no longer required possession of a major harbor. By 1950, almost all of the big guns were scrapped, all the harbor defense commands were dismantled, and the Coast Artillery Corps was abolished as a separate branch of the army. The old coast defense reservations were either converted to other uses by the military or declared surplus.

Civil War & Post-Civil War (1861-1875)

Early Modern Programs (Endicott & Taft, 1886-1917)

Post-WWI Period (1917-1940)

WWII Programs (1940-1950)

US Coast Defense Sites (1945-Present)