Who was William Tutte and how did he help break the Tunny cipher?

William Tutte was a British mathematician and code breaker at Bletchley Park who played a pivotal role in the Allied intelligence project known as Ultra.

In January 1942, Tutte made a critical breakthrough regarding the German Tunny cipher machine. By analyzing intercepted messages, he successfully unmasked systematic patterns within the transmissions. He deduced that the machine used a complex system of 12 internal wheels to generate the "key" used to mask the teleprinter code of the original German messages.

Tutte’s discovery of the machine's internal logic allowed British code breakers to begin reading high-level German military communications regularly. This intelligence provided the Allies with vital strategic information, including details regarding German counter-preparations for the Normandy landings in 1944. His work laid the foundation for the subsequent development of Colossus, the world's first large-scale programmable electronic computer, which was used to automate the decryption process at high speeds.12