Ultra Codebreaking

The Bletchley Park program that read German Enigma traffic in World War II

Overview

Ultra was the intelligence derived from breaking German Enigma and later Lorenz ciphers at Bletchley Park, building on prewar Polish breakthroughs and industrialized by Alan Turing's bombes and the Colossus machines. Decrypts revealed U-boat positions, troop movements, and economic data, and the official historian judged the effort shortened the war by more than a year. The secret held until 1974, requiring thousands to stay silent for decades. The codebreakers' machines are foundational to modern computing. Wartime staff grew to nearly ten thousand, three quarters of them women.