PEARL HARBOR: Magic Was the Word for It

U.S. citizens discovered last week that perhaps their most potent secret weapon of World War II was not radar, not the VT fuse, not the atom bomb—but a harmless little machine which cryptographers painstakingly constructed in a hidden room at Fort Washington.

With this machine, built after years of trial & error, of inference and deduction, cryptographers had duplicated the decoding devices used in Tokyo. Testimony before the Pearl Harbor Committee had already shown that the machine—known in Army code as "Magic"—was in use long before Dec. 7, 1941, had given ample warning of the Jap's sneak attack—if only U.S. brass...