This Month in History: ULTRA's Big Break

During World War II Nazi Germany primarily encoded its messages through the use of what was known as the "Enigma" machine. Enigma’s use by the Wehrmacht stretched back to the early 1930s and originated from a design created by Hugo Alexander Koch in the Netherlands.

Although heavily modified prior to the Second World War’s onset, the Enigma machines used in 1939-1945 remained similar to Koch’s prototypes from two decades prior. For a variety of reasons the Enigma machine was extraordinarily difficult to crack. At it's most basic level breaking Enigma required two things: gathering tremendous amounts of closely guarded information combined with access to an Enigma machine with the proper settings. As to the first element, during the 1930's Poland did much of the heavy lifting in terms of laying the groundwork for breaking the Enigma code. This included creating the “Bomba”, a high-speed calculating machine used to help break Nazi codes and a strong influence on Britain's later, and much more famous, ULTRA code breaking machine and efforts. With Nazi Germany's invasion and occupation of Poland in the fall of 1939 it seemed as if deciphering Enigma may have been fatally delayed. That said, many of Poland's world-class mathematicians and code breakers escaped to help aid the Allied cause.  Though Allied code breakers from across Europe worked feverishly in England, the Allies still needed to acquire an intact Enigma machine if they were to be able to "hack" into (using today's vernacular) German communications.

Over seventy years ago this month, on May 8, 1941, the Allies got their break when a German U-boat, U-110 , attacked an Allied convoy. During the ensuing battle the British escort destroyer HMS Bulldog  (see image) skillfully drove U-110 to the surface. The German captain ordered the crew to abandon ship while he set the charges to scuttle his U-boat. The German captain had made a mistake however, and failed to guarantee the detonators for the charges actually worked. As a result, and as the crew disembarked into captivity, U-110 remained afloat with all her codebooks, charts, and most importantly – a complete Enigma machine. Over the following four hours, while operating from U-110’s slippery decks, and Bulldog’s tiny boarding boat, all in the icy waters off the Greenland coast, the British sailors transferred the valuable Enigma machine, codes and other documents into Allied hands. With this treasure trove of intelligence came the first big intelligence coup for the Allies; one that would play a key role in ultimate Allied victory.