Submarine Warfare

“The only thing that ever really frightened me during the war was the U-boat peril.” — Winston Churchill

The development of practical military submarines introduced a new dimension to naval warfare — the ability to strike from beneath the surface, unseen and often undetected until it was too late. Submarine warfare challenged the dominance of surface fleets and threatened the maritime supply lines upon which industrial nations depended.

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• Units: Submarine

Historical Background

Submersible vessels were attempted as early as the 17th century, and the Confederate H.L. Hunley became the first submarine to sink an enemy warship during the American Civil War in 1864 (though it was lost in the attack). But it was the development of reliable diesel-electric propulsion and the torpedo in the late 19th century that made the submarine a practical weapon of war.

Germany’s U-boat campaigns during both World Wars demonstrated the submarine’s devastating potential. In the First World War, unrestricted submarine warfare nearly severed Britain’s supply lines, sinking millions of tonnes of merchant shipping and contributing to the United States’ entry into the conflict. During the Second World War, the Battle of the Atlantic pitted German U-boat wolfpacks against Allied convoys in a years-long campaign that Churchill later called the most decisive struggle of the war. The development of nuclear-powered submarines in the 1950s — led by the USS Nautilus (1954) — eliminated the need to surface, creating vessels that could remain submerged indefinitely and strike anywhere on the globe.