Shortly after 1:30 am on the 7th of December 1941, the Naval Intercept Station at Bainbridge Island Washington, intercepted a message from Tokyo, bound for the Japanese embassy in Washington DC. The message was in purple, the most secret and complex of the Japanese diplomatic cyphers. As tensions mounted in the pacific, the importance of breaking the enigmatic cypher became all the more pressing. It would become one of the most infamous messages in history.
Credit to : Timeline – World History Documentaries