The large‐scale use of submarines against surface warships began in World War I; both sides employed them in that role. German successes overshadowed those of the Allies, primarily because there were few German surface ships, which robbed Allied craft of targets. Still, both sides succeeded in sinking opposing warships, and the threat of submarines caused commanders to exercise greater caution in using their fleet units.
But it was the attack on Allied merchant shipping by German submarines (Untersee boats or U‐boats) that drew the most attention during World War I. The U‐boats' ability to slip past the Allied naval blockades of German ports allowed them to gain access to British sealanes, attacking shipping headed for Great Britain. When Royal Navy defensive measures made it difficult for surfaced U‐boats to stop merchant ships at sea and board them, the German Navy resorted to “unrestricted submarine warfare,” that is, sinking merchant shipping without warning. Such a German sinking of the Lusitania, in 1915, led to a dramatic worsening of relations with the neutral United States, and the return of the more limited submarine attacks. Germany's political and military leadership gambled in 1917 on a resumption of unrestricted submarine warfare to win the war quickly on neutral as well as belligerent shipping. This prompted the United States to enter on the Allied side in April 1917. Though the Germans sank over 11 million tons of ships, the submarine offensive failed to strangle trade with Britain due to the introduction of protected convoys of merchant ships by the Allies, and the availability of merchant vessels from neutral countries to help replace losses. The threat of submarine attack did compel the U.S. Navy to defend its troopship convoys across the Atlantic, a task accomplished without loss.
The U‐boat campaign of World War II again raised the question of neutral American shipping and the possibility of German attacks. In response, President Franklin D. Roosevelt extended a “neutrality zone” eastward from the North American coast ultimately to Iceland, patrolled by U.S. Navy warships before the official American entry in the war. On several occasions, U‐boats clashed with American warships, in one case sinking the destroyer Reuben James in October 1941. After American entry into World War II, U‐boats initially decimated American East Coast shipping almost with impunity. With the introduction of adequate antisubmarine forces, convoying, and decryption of German naval signals, however, American losses fell dramatically, and the U.S. Navy and Allied forces took the war to the U‐boats in the central Atlantic with deadly effect.
Perhaps the most effective submarine campaign in history was the American Pacific Ocean submarine operation in World War II. This entailed many difficulties initially, including a dearth of bases, faulty torpedoes, and many cautious submarine commanders. Submarine crews spent eight weeks at a time on patrol under cramped conditions and with few amenities. Still, submarines played a vital reconnaissance role from the start of the conflict. Eventually aided by radar, the decryption of Imperial Japanese Navy radio signals (MAGIC), and improved torpedoes, the greatly expanded submarine force scored notable sinkings, destroying one Japanese battleship, eight aircraft carriers, and eleven cruisers. More significantly, the U.S. Navy's submarines crippled Japan's merchant marine, sinking 5.3 million tons, or over half of its ships, in the most successful campaign of the war. Groups of U.S. Navy submarines also emulated the German Navy's “wolf‐pack” tactics to great effect against Japanese convoys. In the war's last days, American submarines ranged over the entire Pacific, even entering the Japanese Inland Sea. But these accomplishments came at a price; 22 percent of submarine personnel died during the conflict, the highest of any American service.
Following World War II, submarines gained new propulsion—nuclear‐fueled. One of the new roles was in antisubmarine warfare, using their own concealed operations, as well as improved sonar and radar, to find opposing submarines. Another was submarine‐launched ballistic missiles as a part of the nuclear deterrent of the superpowers. Submarine combat operations remained limited after 1945, however. Just one ship—an Argentine cruiser—was sunk by a Royal Navy submarine during the Falkland War in 1982.
[See also Navy Combat Branches: Submarine Forces; Submarines.]
Edward Beach , Run Silent, Run Deep, 1955.
Clay Blair , Silent Victory, 1975.
Mark P. Parillo , The Japanese Merchant Marine in World War II, 1993.
I. J. Galantin , Submarine Admiral, 1995.
Clay Blair , Hitler's U‐Boat War, 1996.
Peter Padfield , War Beneath the Sea, 1996.