The Battle of the Atlantic was perhaps the most essential front for the war in Western Europe during the years 1939 to 1944 at least. This was a battle at sea between the Royal Navy, American Navy and the German U-boats under the command of Admiral Donitz. Donitz was convinced that submarine warfare was the navy's most effective weapon and the most likely way to defeat Britain. As the Luftwaffe aircraft crashed out over Britain in 1940, this seemed to reaffirm this; and the loss of the Bismarck further highlighted that the Kriegsmarine could not match Britain’s surface fleet.
As such, the Nazis organized U-boats into Wolf Packs for the battle. During the first couple of years they held the advantage in the Battle of the Atlantic, and sank thousands of merchant ships. This was especially the case after June 1940 when France was defeated and accepted an armistice with Germany. After this, the Kriegsmarine had greater access to the Atlantic with new submarine pens established in France. A big increase in British merchant ship losses followed.
May 27, 1941
However, this did not convince all within the German Navy High Command that they should abandon surface fleet action in favor of the U-boat campaign. This was partly down to the Bismarck, the largest battleship of the Kriegsmarine that eclipsed 50,000 tons. The Royal Navy sent a couple of battleships to sink the Bismarck, and they intercepted the ship. Even though Britain lost the Hood, by May 27 the Royal Navy had sunk the Bismarck. The loss of this great battleship ensured that there was now little doubt that the U-boat campaign be given priority. Further to this, it saved British merchant ships from the Bismarck’s guns.
October 31, 1941 and December 7, 1941
In October of 1941, U.S. involvement in the Battle of Atlantic increased. This was partly due to the sinking of the Reuben James on October 31, 1941 by a U-boat. This was the American’s first lost ship in the war, months before they were officially at war with Germany. The USA joined Britain in the war after Pearl Harbor on December 7.
October 30, 1942
The Battle of Atlantic did not get any better for the Allies in 1942. British merchant ship losses reached their highest levels, and now it seemed that the U-boats were closer to victory than at any point before. However, the sinking of the U-559 submarine by the Royal Navy on October 30, 1942 was a pivotal turning point in the battle.
This submarine also stored German cryptographic material required to break the Enigma cipher. British sailors seized this before the submarine sank, after its crew had abandoned the submarine. With that the Allies had broken the Enigma cipher and could now detect the U-boats much sooner, saving many merchant ships and ensuring greater U-boat losses.
The impact of this began to tell by April 1943; although the Nazis remained completely unaware that the British had seized cryptographic material from their lost submarine. U-boat losses escalated during this period, so Allied merchant ship losses were greatly reduced. As such, by May 1943 it had become clear that the Kriegsmarine could no longer win the U-boat campaign and the Germans withdrew the submarines. While the battle did not end here, it was still lost.
These were just a few of the notable dates of the Battle of the Atlantic. The loss of the Bismarck, Reuben James and the U-559 submarine were all notable dates in the campaign. The U-boat menace had evaporated by 1945 as German submarine pens were lost.