Famous as ‘the man who broke Purple’. Friedman was born in Russia but was taken by his family to America in 1896. He began his work in military codebreaking with the American Army in 1917 and worked at Expeditionary Force Headquarters in France in 1918. He continued in government service between the wars, ably assisted by his wife Elizabeth, also a remarkably gifted cryptographer, and in 1940 succeeded in breaking the secret of the Japanese diplomatic cypher known to the Americans as Purple. The failure of the American government to forewarn their armed services of the attack on Pearl Harbor despite the access Friedman’s achievement gave them to Japanese diplomatic traffic, remains one of the mysteries of World War II, though it is now regarded as less sinister than has been thought. Friedman’s work on Purple was so intensive that he suffered a nervous collapse and achieved nothing of comparable importance in code-breaking during the rest of the war.