Existing comment:
Hunter-Killer Group:
Because the United States could more than replace its losses, it had a great advantage over its enemies. When the numbers of escorts produced exceeded the number needed for convoy duty, the United States Navy's hunter-killer groups sought out German submarines.
A Game of Chess:
During World War II, the North Atlantic Ocean became a vast chessboard on which a deadly serious game was played. On one side was the German navy, intent on strangling the flow of foodstuffs and goods to England. The navies of the United States, England, and Canada lined up on the opposite side. The pieces on the board were U-boats and merchant ships. The prize was the survival or fall of Great Britain.
"The Happy Time":
During the first six months of war, German submarines sank 100 vessels along the American eastern seaboard. In this same period, Americans sunk only six German U-boats. Lax blackout practices along the east coast of the United States made it easy for the German subs -- the bright lights of coastal cities silhouetted merchantmen.
By July 1942, German submarines were sinking an average of three merchant ships each day. German submarines called this "The Happy Time."
Convoys:
Relying on lessons learned in World War I, the British Admiralty believed that escorting merchant convoys and using the underwater sound-tracking device called ASDIC would eliminate the threat posed by German submarines.
Upon the outbreak of war in 1939, the Admiralty ordered that ships that could make less than 15 knots travel in convoy; faster ships would sail alone. By the end of the year, only four of the 6,000 convoy ships had been lost, while 102 independently routed ships were sunk.
Wolfpacks:
At first, German U-boats operated independently, but by the fall of 1940, their commander, Adm Karl Donitz, began deploying them in picket lines. By coordinating their attacks, the U-boats were like a pack of wolves hunting caribou.
Radio communication was critical to Donitz's strategy. After gathering information about the location of Allied convoys, Donitz broadcast this intelligence in code to his U-boats. Eventually, the Allies were able to intercept and decipher Donitz's broadcasts, and tried to reroute convoys.
Hunter-Killer Groups:
By mid-1943, the Allies finally had enough forces to go on the offensive against the German U-boats. A half dozen old destroyers and destroyer escorts, along with an escort carrier, went on the hunt. They used radar and sonar to locate enemy submarines and sink them with depth charges, hedgehogs, and aerial bombs. Hunter-killer groups effectively reduced losses of Allied merchant ships.
Checkmate:
The convoy approach was successful. Of the 2,275 merchant ships destroyed by U-boats, only 28 percent were in convoys. By war's end, the Allied had completed 300,000 crossings of the Atlantic.
The fast pace of Allied shipbuilding was another factor in the demise of Axis power. The Germans could not keep up, especially given U-boat mortality rate, the highest of all service branches in the war. Three-quarters of U-boat sailors died. If Germany had started with 200 boats instead of 50, the Battle of the Atlantic might have ended differently. |