World War II, U.S. Naval Operations in: The North Atlantic

World War II, U.S. Naval Operations in: The North Atlantic. During World War II (1939–1945), Germany attempted to isolate Great Britain by severing the North Atlantic sealanes by submarine warfare. Initially, the Kriegsmarine Untersee‐Waffe commander, Adm. Karl Doenitz deployed submarines into England's southwestern approaches, where they nearly crippled Allied shipping. The effectiveness of this operation increased substantially when France and the Low Countries capitulated in spring 1940, giving the Germans U‐boat bases on the Atlantic. During the war's first two years, German submarines sank more than 1,200 Allied ships and severely hampered England's supply systems.

In the fall of 1941, with U.S. Lend‐Lease supplies to Britain in jeopardy, President Franklin D. Roosevelt ordered U.S. naval warships to begin escorting Allied convoys. On 4 September, after evading a torpedo from a German submarine, the destroyer USS Greer launched a depth charge attack against the U‐boat. Roosevelt then ordered the navy not to wait until attacked but to shoot German submarines on sight. Eight weeks later, after several other confrontations, a German submarine sank the USS Reuben James. Before the attack on Pearl Harbor, U.S. naval forces were fighting in a major if undeclared naval war with Germany in the North Atlantic.

After the United States entered the war in December 1941, U‐boats began patrolling off the American East Coast and in the Gulf of Mexico, where they unleashed Operation Paukenschlag (Drumbeat) to destroy American shipping. In four months the Germans sank more than 360 ships, including the destroyer USS Jacob Jones. Caught off guard, the U.S. Navy had failed adequately to protect commercial coastal vessels, which were often gunned down by surfaced U‐boats using East Coast city lights to silhouette their targets.

Because U.S. naval forces were spread thin across the Atlantic and Pacific, the chief of naval operations, Adm. Ernest J. King, decided against using a coastal convoy system. Instead, in what was later called the “Bucket Brigade,” merchant captains were advised to sail close to America's shorelines by day and to dash into the nearest harbor at night.

The British criticized King for not providing proper antisubmarine warfare (ASW) defenses. After carefully convoying ships across the Atlantic and into American waters, the U.S. Navy was allowing too many merchant ships to fall prey to the enemy along the coast. Upon transferring several British ASW escort ships to the U.S. Navy, Prime Minister Winston S. Churchill suggested that America inaugurate a coastal convoy system.

In May 1942, after continued losses, King did institute such a system, and assigned land‐based airplanes and blimps to patrol along the Atlantic seaboard. As these pressures increased, the U‐boats withdrew from East Coast waters and reconcentrated in the Gulf of Mexico and Caribbean Sea, where they sank another 160 ships.

During the fall of 1942, Doenitz ordered his submarines into the mid‐Atlantic, which was free of Allied air cover. Here, in an area called the “Black Pit,” the Germans in their continuing assault against convoys instituted Rudel taktik (wolf pack tactics). Initially, these attacks on convoys by groups of submarines were quite successful. However, by the summer of 1943, improved ASW tactics, better training, and new technology began extracting a toll on the U‐boats.

The Battle of the Atlantic was ultimately a conflict of attrition: numbers of vessels sunk versus new ships constructed, and numbers of U‐boats sunk versus new submarines constructed. As time passed, the Allies amassed great quantities of merchant ships, war vessels, ASW weapons, and sophisticated equipment. Improved radar, sonar, and radio direction‐finding systems, coupled with extensive use of airpower, slowly turned the tide of war against the U‐boats.

Intelligence gathered from ULTRA and the decoding of U‐boat and other German radio transmissions allowed the rerouting of convoys around the wolf packs. Destroyers equipped with radio direction finders located U‐boats, drove them underwater, and dropped depth charges on them. Airborne and shipborne radar was significant in spotting surfaced submarines. U.S. patrol planes flying over the Bay of Biscay used radar to find and attack surfaced U‐boats transiting in and out of French ports.

In addition to these technical advances, organizational reforms aided the U.S. Navy's effort. During the spring of 1943, Admiral King consolidated all ASW research, training, weapons procurement, and strategy under one command, the Tenth Fleet. Under his authority, the Tenth Fleet coordinated and streamlined all Atlantic operations.

A turning point in the Battle of the Atlantic occurred in the spring of 1943, when the U.S. Navy began using long‐range, land‐based aircraft and escort carriers to patrol the mid‐Atlantic. Planes such as PBY Catalinas and B‐24 Liberators provided extensive convoy coverage across the “Black Pit.” Flying from Iceland, a B‐24 Liberator (with depth charges aboard) could enter the mid‐Atlantic and patrol above Allied vessels for nearly four hours. Many of these planes successfully attacked and destroyed U‐boats. On occasion, patrolling aircraft forced U‐boats into deep water dives, where for extended periods they were unable to threaten the convoys. In May 1943 alone, the Germans lost more than forty submarines.

American hunter‐killer groups, typically composed of one escort carrier and three destroyers, substantially enhanced the U.S. Navy's ability to defend the convoys. Often, in the mid‐Atlantic, after forcing U‐boats to crash‐dive, carrier planes dropped homing torpedoes on the submarines. One particular success occurred on 4 June 1944, when the crew of the escort carrier Guadalcanal captured U‐boat 505 on the surface, along with all of its codebooks and sophisticated equipment.

In part because of these successes. Germany was unable to block the men and material necessary for the invasion of Normandy and the D‐Day landing. By war's end, Doenitz's U‐Waffe was depleted. While his submarines sank more than 2,700 Allied ships, they also lost nearly 800 U‐boats and 28,000 sailors. Yet there were no spectacular, Midway‐style decisive battles for the U.S. Navy in the Atlantic as there were in the Pacific. Instead, for U.S. naval forces, the battle consisted of endless days of searching for elusive U‐boats and once one was found, of launching a prolonged attack upon the submerged enemy.

After the war, because most documents remained long classified, a myth of the highly successful U‐boat campaign developed. However, newly declassified documents have indicated that because of torpedo and other technical problems, U‐boats were much more vulnerable to ASW attacks than previously thought. The evidence also reveals that the submarines destroyed only a very small percentage of the ships crossing the Atlantic. This new evidence, however, has not distracted from the difficulties and the bitterness of one of history's longest and most complex naval campaigns.
[See also Antisubmarine Warfare Systems; Submarines; World War II: Military and Diplomatic Course; Strategy: Naval Warfare Strategy.]

Bibliography

Samuel Eliot Morison , The Battle of the Atlantic: September 1939–May 1943, Vol. 1, 1947; and The Atlantic Battle Won: May 1943–May 1945, Vol. X, 1956.
Dan Van der Vat , The Atlantic Campaign: World War II's Great Struggle at Sea, 1988.

Donald D. Chipman