2 Dec 1941-"Climb Mt. Niitaka" is transmitted from Tokyo to the Imperial Japanese Fleet

On 2 December, 1941, a powerful force of Japanese aircraft carriers, cruisers and destroyers were en route to Pearl Harbor, Hawaii. A smaller force was also en route to Singapore, home of the Royal Navy fleet guarding the British Empire in Asia. Both forces got underway on 26 November, awaiting the attack order/no attack order from Imperial Japanese Navy headquarters. The order to attack was dependent on the satisfactory conclusion of negotiations between the Japanese diplomats in Washington, who were holding regular meetings with U.S. Secretary of State Cordell Hull. If the negotiations were successful, the fleet would turn back. If not, the diplomats were to present the U.S. with a declaration of war, and the attack would commence.

The Japanese had been studying how to attack Pearl Harbor for years. They had modified their aerial torpedoes so that they could operate in the shallow waters of the Pearl Harbor anchorage, and the commander of the Japanese Navy, Admiral Yamamoto, had studied at the U.S. Naval War College. He knew his American counterparts very well, particularly their schedules. Saturday night was normally set aside for entertainment and poker playing (Yamamoto was an excellent card player), and Sunday was a day of rest, with liberty and church services for all hands. Sunday morning would be the best time to attack the fleet at Pearl Harbor, as operational readiness would be at the lowest point.

All the fleet needed to hear for the attack was a simple code phrase, which was “Climb Mt. Niitaka”. Niitaka is the highest mountain on Taiwan, which in 1941was a Japanese possession. The mountain had been climbed successfully in 1900 by a team of Japanese climbers, who named the mountain Niitaka, which means “new high mountain”. This name was given because Niitaka is even higher than sacred Mount Fuji on the island of Honshu. Niitaka is also a very difficult ascent, extremely challenging with a high chance of failure.

When the code phrase was transmitted, U.S. Navy cryptologists intercepted and translated it, but the phrase had no meaning. For the fleet commanders the meaning was perfectly clear. It meant that negotiations in Washington were not proceeding to Japan’s advantage, the the U.S. had no intention of lifting the oil and scrap metal embargo until Japan disengaged from its war in China and pulled its troops out of French Indochina (which after World War II would become the nations of Vietnam, Cambodia and Laos, but that’s another story), so the only alternative was war. The code phrase meant that all aircraft carriers and supporting ships were to be in place to attack Pearl Harbor and Singapore by 7/8 December. 7 December for Pearl Harbor, as it lay on the opposite side of the International Date line, and 8 December for Singapore.