Major Events

The capturing of U-110, a German U-boat, gave the Allies useful information about the Enigma which allowed them to read the Naval Enigma communications for several months (Wilcox 2002, 18). Later, the capture of U-559 also provided critical information which allowed the Allies to read Enigma transmissions (Grimsley 2010).

U-110 and HMS Bulldog. Courtesy of Wikimedia Commons.

Minor Events

In the early years of Bletchley Park, the cryptanalysts realized that some of the German clerks running the Enigma machines would use predictable text as their indicators. A notable example was when a clerk used his girlfriend’s name as his indicator. These encounters in particular would be known as “Cillies.” Utilizing these predictable indicators allowed some Enigma encryptions to be decrypted more easily (Wilcox 2002, 10).