The breaking of the Enigma code shortened the Second World War by at least a year. Successful espionage and strategic deception underpinned the Allied invasion of Sicily and the D-Day landings. The Soviet penetration of Western intelligence in the 1930s and 1940s gave Stalin a crucial advantage in his dealings with the West. The pantheon of world-changing spies is small and select, and Oleg Gordievsky is in it:
