It was early morning, Thursday, Dec. 4, 1941, when senior radio operator Ralph Briggs came on duty to his post at the U.S. Navy shortwave monitoring station in Maryland. The radio crackled as he tuned his receiver to a specific station in order to begin daily monitoring of the regional weather forecast from Radio Tokyo, Japan.
He began transcribing what he heard.
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A few miles away, at the Japanese Embassy in Washington, D.C., Chief Petty Officer Kenici Ogemoto also was listening to the weather report. When he heard the words, he rushed into the office of the naval attaché, Capt. Yuzuru Sanematsu, and shouted, "The winds blew!"
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Dutch naval intelligence in the Dutch East Indies, led by Lt. Gen. Hein Ter Poorten, had succeeded in intercepting and decrypting the Japanese naval message at their intercept station on Java Island.
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What all three men heard at 8 a.m. that day were words each was waiting for.
"Higashi no kaze ame." "East Wind, Rain."
Each of them knew what those words meant. They were one of three possible execute messages that Japanese diplomats around the world were told to listen for beginning on November 19. Those three words, meant war with the United States.
Briggs understood this and immediately began to teletype the message to Washington.
Poorten immediately sent all the details of the "Winds Execute" message to Col. Weijerman, the Dutch military attaché in Washington, to pass on to the highest U.S. military authorities.
At the Japanese Embassy, Ogemoto and Sanematsu directed the staff to gather all secret papers for burning, and prepare to destroy all code hardware and cipher codes.
Meanwhile, in Tokyo, Japanese officials were going over the final note to the American government. The note will not include a simple declaration of war. Instead, it would say, ”In view of the attitude of the American Government it must be concluded that it is impossible to reach an agreement through further negotiations."
The Japanese officials decide this note will be delivered at 1 p.m., Washington time. Thirty minutes before the surprise attack.
Back in the U.S., and at stations around the world, the monitoring of Japanese transmissions continues.
On Friday, Dec. 5, "All Japanese international shipping has returned to home port."
On Saturday, Dec. 6, Japan, "Sends the first segments of a 14-part message to its embassy in Washington, ordering them to present their final demands to the United States at 1 p.m. Washington time, tomorrow."