Like the September 11, 2001 attacks, it appears that lack of co-ordination and bad luck prevented America from preparing for the Japanese attack on Pearl Harbor on December 7, 1941. There was plenty of warning.
America had cracked the Japanese diplomatic codes — Purple and JN-25 — and was aware that Japan was becoming hostile, but nobody “connected the dots”. (We’d not yet broken their naval code. In any case, the Japanese naval task force maintained radio silence.)
Air Corps Lt. Kermit Tyler, on his second day in charge of a new 106 MHz transportable radar station on Hawaii’s Opana Point, didn’t report radar detection of incoming aircraft. (A fighter pilot, he thought that the SCR-270 radar had detected a flight of B-17s that was expected to arrive that morning.) At 7:02 AM, his two brand-new untrained radar operators had detected some of the incoming 354 Japanese fighters and bombers. Estimated range was 132 miles. Estimated ground speed was 180 MPH. The two operators continued to track the planes until 7:40 AM. Lt. Tyler, certain that they were tracking the incoming B-17s, told his two radar operators, “Don’t worry about it. Let’s have breakfast.”
At 6:37 AM, our destroyer Ward detected and used depth charges to sink a submarine in Pacific waters outside Pearl Harbor. Pearl Harbor’s commanding officer, Admiral Kimmel, received the radioed report via telephone at 7:30 AM, discussed it via telephone with Rear Admiral Claude Block, and at 7:50 dispatched a destroyer to confirm the Ward’s report.
Pearl Harbor came under attack at 7:55 AM.
Listen to the American broadcast radio response to the attack on Pearl Harbor. Includes news reports, man in the street interviews, FDR’s “day of infamy” congressional address, and his fireside chat.