Defending America's Coastline

Facing advances in military technology and weaponry, the US looked to upgrade coastal defense systems around the turn of the 20th century. In many harbors, controlled submarine mines were installed. Learn about the role of the Boston Harbor Islands in monitoring the controlled submarine mine system during the World Wars.

The events of World War II transformed Kiska Island in the Aleutians into a cultural landscape that is truly unique on a global scale. Reminders of the Aleutian Campaign on Kiska remain visible today.

Constructed during World War II, this concrete and steel fire control station was most important in Harbor Defenses of San Diego in that the battery commander of 16-inch-gun Battery Ashburn operated from the top level (BC3) directing the fire of his guns. The lower level (B1/3 S1/3) served as one of five base end stations for Ashburn.

Fort Cronkhite, located just north of San Francisco, was a WWII Coast Artillery military post that was part of the Harbor Defenses of San Francisco. Fort Cronkhite served Battery Townsley, a 16-inch gun that, constructed with Battery Davis at Fort Funston, was designed to protect San Francisco and the Golden Gate straights from enemy attack.

During World War II, the U.S. Army and Navy arrayed a vast network of coastal fortifications, underwater minefields, antiaircraft guns, radars, searchlights, observation posts, and patrol aircraft, to protect the all-important entrance to the harbor, the Golden Gate and its famous bridge.

Many national park sites joined the war effort in World War II by erecting Aircraft Warning, radio and radar stations. Some historic forts came to life with coastal defenses ready to defend the nation.

Abandoned coast guard stations and aircraft warning station lookouts remind visitors of the frightened and earnest efforts made at coastal defense in the earliest days of World War II on the Olympic Peninsula.

The wartime demand for manpower and the racial policy of the Roosevelt administration caused the Marine Corps to agree in February 1942 to accept African-American recruits for the first time since the Revolutionary War, when a few blacks had served in the Continental Marines. Many of these men defended America's coasts and served abroad in theaters of war.

In the spring of 1942, German U-boats prowled the ocean off the Outer Banks of North Carolina and sank freighters at will. By June, they had sunk 397 merchant vessels and the area earned the name "Torpedo Junction."

Battery Jasper, part of Fort Sumter and Fort Moultrie National Historical Park, is located on Sullivan's Island. It served as the primary Endicott System battery from 1898 - 1943.