Designed by British telephone engineer Tommy Flowers, ‘Colossus’ was built to speed up code-breaking of the complex Lorenz cipher used in communications between Hitler and his generals during World War II. It is widely thought to have shortened the war and saved countless lives.
On February 5, 1944 Colossus Mk I worked on its first Lorenz-encrypted message. By the end of the war, 63 million characters of high-grade German messages had been decrypted by the 550 people working on the 10 functioning colossi during the war.
Colossus occupied the size of a living room (7 feet high by 17 feet wide and 11 feet deep), weighed five tons, incorporated 2,500 valves and 10,000 resistors connected by 7 km of wiring. Its existence was kept top secret for 30 years because of the sensitivity surrounding the encryption messages it had helped to break.