A major factor in the success of the Allies from the second half of 1941 onwards was the cracking of the Enigma machine. Enigma was the name of a family of ciphering machines that used a complicated system of substitution alphabets and rotor machines which made German military transcripts almost impossible to crack by Allied intelligence. Polish Military Intelligence made the first significant breakthroughs in the 1930s but the constantly evolving system meant that it was a continuous battle to unravel this complex system. This was particularly true of the German Navy’s Enigma ciphers which had always used more secure procedures. Thus it was crucial that cipher material be captured at sea to assist in the code-breaking. The first capture of Enigma material occurred in February 1940, when rotors VI and VII, the wiring of which was at that time unknown, were captured from the crew of U-33. On 9 May 1941, the Royal Navy captured U-110 with a complete Enigma machine, codebook, operating manual and other crucial information. Naval Enigma machines or setting books were captured from a total of seven U-boats and eight German surface ships during the war. One such captured U-boat was U-505, a Type IXC U-boat captured by the USN in 1944. The U-boat was towed back to America and the crew rescued. However, to protect the secret of the capture of the vital Enigma materials the prisoners were isolated from other POWs, the Red Cross was denied access to them, and their families were informed that they had all been killed. The Enigma materials were eventually forwarded to Bletchley Park, the secret site of British code breaking operations where they helped to continue cracking German naval codes and assisted in the eventual Allied victory in the Battle of the Atlantic. Today the U-505 is on display at the Museum of Science and Industry in Chicago.
Second Funkmaat Willi Anderheyden, of U-564 on duty in the radio room and at work on the four-rotor Enigma machine introduced in 1942. Note his casual style of dress.