“Climb Mount Niitaka”

At 5.30 p.m. Tokyo time on 2 December 1941 the Japanese navy sent its ships in the Pacific a brief message: “Niitakayama nobore 1208” – “Climb Mount Niitaka, 1208”. For Vice Admiral Chūichi Nagumo’s carrier force, which had been sailing towards Hawaii for a week, and for every other force of the fleet, the message meant one thing: war would begin on 8 December, Tokyo time. In Washington it was then early morning on 2 December, and in Hawaii the evening of 1 December. American diplomats were still talking to the Japanese ambassadors, and none of the American listening posts could read the signal.

Under 2 December one comes across the statement that Prime Minister Hideki Tōjō rejected American “peace feelers”. Put that way, it is inaccurate. At the beginning of December the United States was not making Japan any new peace proposals, and the decision for war was not taken on 2 December by Tōjō alone: it had been taken the day before by an Imperial Conference attended by the Emperor, the government and the high command. The talks in Washington went on for another week, but for Tokyo they were by now merely a screen for the preparations to attack.

The Imperial Conference of 1 December

A conditional decision for war had been taken by the Imperial Conference of 5 November: if no agreement with the United States was reached by 1 December, Japan would go to war with the United States, Britain and the Netherlands. General Tōjō’s government, which had taken power in October, sent its final proposals to Washington, but the reply was the Hull note of 26 November, which demanded the withdrawal of Japanese troops from China and Indochina. Tokyo regarded it as an ultimatum. The country’s leaders were no longer asking whether to go to war, only how to begin it.

The last doubts were voiced by the Emperor’s own circle. On 29 November Hirohito heard the former prime ministers, some of whom, among them Admiral Mitsumasa Yonai, warned against a war without assured resources. On 30 November the Emperor’s younger brother, Prince Nobuhito Takamatsu, a naval officer, told him that in its heart the navy doubted it could wage war for more than two years. On the advice of the Lord Keeper of the Privy Seal, Kōichi Kido, the Emperor summoned the Navy Minister, Admiral Shigetarō Shimada, and the Chief of the Navy General Staff, Admiral Osami Nagano. Both assured him that the fleet was ready and that the war would be a success.

The conference met in the Imperial Palace on the afternoon of 1 December. Tōjō outlined the situation, the Foreign Minister, Shigenori Tōgō, reported on the course of the negotiations, and the chiefs of staff – Nagano and General Hajime Sugiyama – on the state of military preparations. The questions were put, as usual on behalf of the silent Emperor, by the President of the Privy Council, Yoshimichi Hara. A one-sentence resolution was adopted: negotiations with the United States on the policy settled on 5 November had finally failed, and the Empire would therefore go to war with the United States, Britain and the Netherlands. According to the minutes, Tōjō closed the meeting by saying that the Empire stood on the threshold of glory or ruin.

The conference did not settle how and when the Americans were to be informed. It was decided that the note ending the negotiations would be handled jointly by the Foreign Ministry and the high command. At a liaison conference on 4 December the text was entrusted to Tōgō, who was to fix the time of its delivery with the high command. According to Tōgō’s testimony before the Tokyo tribunal, the chiefs of the naval staff asked that the talks should not be broken off before the attack, so that the blow would come as a surprise.

Climb Mount Niitaka

On 2 December Nagano and Sugiyama presented the Emperor with the date for the start of operations, known in the staffs as X-Day, and Hirohito approved it. The orders went out that same afternoon. According to Japanese studies, the navy’s message was sent by the transmitter at Funabashi near Tokyo, which handled communications with surface ships, while submarines received it through a long-wave station. The words were turned into five-figure groups with a codebook, so that even if intercepted the message looked like any other.

The code phrase was chosen with its overtones in mind. Niitaka, today Yu Shan on Taiwan, is 3,952 metres high and, from the annexation of the island in 1895, had been the highest peak of the Empire, higher than Fuji. “Climbing Niitaka” meant undertaking the supreme task, and the figures “1208” gave the date: the twelfth month, the eighth day. The army sent its own signal to its forces in the south, “Hinode wa Yamagata”, in which “sunrise” stood for X-Day and “Yamagata” for the eighth day of the month. Post-war accounts also mention signals for calling off the attack, “Tsukubayama hare” for the army and “Tonegawa kudare” for the navy, but there are no documents that reliably confirm them.

The message did not change the plan; it set it in motion. Nagumo’s force, six carriers and their escort, was sailing across the North Pacific under radio silence. On 3 December it reached its waiting point, refuelled and turned south-east. The order of 25 November provided that the force would turn back if the negotiations produced an agreement. After 2 December that possibility no longer existed. The commander of the Combined Fleet, Admiral Isoroku Yamamoto, the author of the attack plan, directed the operation from the battleship Nagato at anchor in Hiroshima Bay.

At the same time Tokyo began to cover its tracks. On 1 December the Foreign Ministry instructed the embassies in London and Hong Kong and the consulates in Singapore and Manila to destroy their cipher machines, and on 2 December it told the embassy in Washington to burn its codebooks and destroy all its machines but one. The Americans read these messages thanks to the breaking of the Japanese diplomatic ciphers. The destruction of ciphers was one of the clearest signs that war was approaching, and on 3 December Washington informed the commands in the Pacific. Where and when Japan would strike, the diplomatic messages did not say.

The President’s question

Tension in Washington was heightened at the end of November by words attributed to Tōjō. A speech read out in his name at a rally marking the anniversary of the treaty with Wang Jingwei’s puppet government in Nanjing spoke of purging East Asia of British and American influence. President Franklin Delano Roosevelt cut short his stay at Warm Springs and returned to the capital on 1 December. That day Secretary of State Cordell Hull took Ambassador Admiral Kichisaburō Nomura and the special envoy Saburō Kurusu to task over the Prime Minister’s “loud talk”. Kurusu promised to supply a correct translation and assured him that the Japanese proposal of 20 November still stood.

On 2 December Hull was unwell, and the two Japanese were received by the Under Secretary of State, Sumner Welles. He read them a question from the President. Roosevelt wrote that he was receiving reports of a rapid build-up of Japanese forces in southern Indochina, far larger than the agreement with the Vichy government of July allowed. Such large forces were not needed to keep order, and might therefore be used for fresh aggression: against the Philippines, the Netherlands East Indies, Burma, Malaya or Thailand. The President asked what the reasons for these steps were and what the policy of the Japanese government was.

Nomura replied that his government had not informed him of its intentions, but that he would pass the question on to Tokyo. He added that the Japanese regarded economic sanctions as a more effective weapon than military force and would rather fight than yield to pressure, and that any agreement was better than none. Welles answered that the United States had no aggressive intentions towards Japan and that its proposal would give Japan peace and meet its economic needs.

Tokyo’s reply came on 5 December and was evasive. The Japanese government stated that Chinese troops had recently been active on the northern border of Indochina, so the garrisons there had been reinforced, chiefly as a precaution. The troop movements in the south, Tokyo claimed, were merely a natural consequence of this step, reports of them were exaggerated, and Japan had not violated the protocol on the joint defence of Indochina concluded with France. Hull remarked that this was the first time he had heard of Japan defending itself in Indochina against the Chinese. When the conversation turned to aid for China and for Germany, Nomura muttered in Japanese, according to the American interpreter’s note, that “this is getting nowhere”. It was the Japanese diplomats’ last conversation with Hull before 7 December.

At sea: 4 December

While the diplomats were exchanging notes, Japanese forces all over the Pacific were moving into their starting positions. On the morning of 4 December a convoy carrying the first echelon of General Tomoyuki Yamashita’s 25th Army, with its commander aboard, left Samah Bay (today Sanya) on the island of Hainan. Some twenty transports carried troops of the 5th Division, who were to land at Singora (Songkhla) and Patani on the Thai coast of the Kra Isthmus, and a detachment of the 18th Division destined for a landing at Kota Bharu in British Malaya. The convoy was covered by Vice Admiral Jisaburō Ozawa’s ships, with the heavy cruiser Chōkai, and at a distance by Vice Admiral Nobutake Kondō’s force with the battleships Kongō and Haruna. Transports from the ports of Indochina joined along the way.

This was not the only movement. General Hisaichi Terauchi’s Southern Army (Nampō-gun) in Saigon was responsible for the whole offensive in the south. Army and navy aircraft were concentrating on airfields in Taiwan and southern Indochina, landing forces bound for the Philippines were waiting on Taiwan, in the Pescadores and at Palau, and the detachment that was to take Guam was setting out from the Bonin Islands. The 38th Division took up position on the border of the New Territories of Hong Kong, and at Kwajalein a force was preparing to capture Wake atoll. More than twenty submarines of the 6th Fleet were closing in on Oʻahu.

The Americans saw only part of these preparations. For a week radio intelligence in Hawaii had heard nothing from the Japanese carriers and assumed they were in their home ports. Meanwhile Admiral Husband Kimmel had sent both carriers based at Pearl Harbor to deliver aircraft to the garrisons of Wake and Midway, so on Sunday 7 December neither of them was in Pearl Harbor.

6 December: a Hudson over the Gulf of Siam

The first contact came on 6 December over the South China Sea. A Lockheed Hudson reconnaissance aircraft of No. 1 Squadron, Royal Australian Air Force, which had taken off from Kota Bharu, sighted a cruiser and several transports shortly after midday, near the limit of its range. The pilot, Flight Lieutenant John Ramshaw, went lower, and moments later his crew reported a large, strongly escorted convoy steaming west, some 80 nautical miles south of Cape Cambodia (Cà Mau). According to the British official history, the reports spoke of twenty-two ships in one group and of a second convoy spotted by another aircraft.

At that stage the convoys might have been heading deep into the Gulf of Thailand, towards Bangkok, or towards the Kra Isthmus. The British Commander-in-Chief in the Far East, Air Chief Marshal Robert Brooke-Popham, had a plan ready, Operation Matador, for British troops to enter southern Thailand before the Japanese did. The government in London, however, did not want Britain to be the first to violate Thai neutrality, and Brooke-Popham was under orders to avoid offensive action until Japan attacked. He did not launch the plan and did not allow the convoy to be attacked. The troops in Malaya were put on the highest state of readiness. Bad weather broke contact with the convoys. The next day Japanese fighters shot down over the gulf a British Catalina flying boat sent out to search, and its crew were killed before they could send a report. It is often regarded as the first aircraft lost in the Pacific War, even before the war formally began.

On Saturday 6 December news of the convoys reached Washington and, via the British, the commands in Hawaii. It confirmed what had been expected: that Japan would strike in South-East Asia. No one connected it with Pearl Harbor.

A message to the Emperor and a message in fourteen parts

On the evening of 6 December Roosevelt decided on a step that Kurusu himself had in fact been urging for weeks: a personal appeal to the Emperor. At 9 p.m. Washington time the State Department sent the text to the ambassador in Tokyo, Joseph Grew. The President recalled that almost a hundred years earlier a President of the United States had offered Japan friendship, described the threat to the Philippines, the Netherlands East Indies, Malaya and Thailand posed by the troops massed in Indochina, and wrote that none of these peoples could sit indefinitely on a keg of dynamite. He gave an assurance that the United States had no intention of entering Indochina if Japan withdrew all its soldiers from there, and that he would seek the same assurances from the Dutch, the British, Thailand and even China. He ended with an appeal for the two rulers to prevent “further death and destruction”.

The message reached Tokyo at about midday on 7 December, Tokyo time, but on the army staff’s instructions the telegraph office held it back for some ten hours. Grew received it only late in the evening and just before midnight took it to Tōgō, asking for an audience with the Emperor. Tōgō took the text to the palace and read it to Hirohito at about 3 a.m. on 8 December, together with the government’s reply, which had already been prepared. By then the Japanese were already landing in Malaya and Nagumo’s aircraft were approaching Oʻahu.

At the same time Japan’s reply to the Hull note was flowing from Tokyo to the embassy in Washington. On the morning of 6 December, Washington time, the Foreign Ministry announced a long memorandum in fourteen parts and ordered that it be kept secret pending separate instructions. Thirteen parts arrived during the day, and American cryptanalysts had decoded them by that evening. At about 9.30 p.m. they were brought to the White House. According to the naval officer who delivered them, Lieutenant Lester Schulz, Roosevelt read the text in the presence of Harry Hopkins and said: “This means war.” The fourteenth and final part arrived during the night, and on the morning of 7 December came the instruction to hand the whole document to the Secretary of State at 1 p.m. Washington time, that is 7.30 a.m. in Hawaii. The document stated that further negotiations could not lead to agreement, but it neither broke off diplomatic relations nor declared war. The embassy failed to finish decoding and typing out the text in time, and Nomura and Kurusu did not stand before Hull until 2.20 p.m., roughly an hour after the first bombs fell on Pearl Harbor.

Place in the war

The first week of December 1941 was a week in which the decisions had already been made and diplomacy served only to conceal them. The conference of 1 December closed the road to agreement, the signal of 2 December fixed the date, and the President’s question of 2 December and the Japanese reply of 5 December, like the last messages of 6 and 7 December, could no longer change anything. The Americans were reading Japanese diplomatic correspondence and saw the destruction of ciphers and the convoys off the coast of Indochina, but they did not penetrate the secret of Nagumo’s force. They expected a blow in South-East Asia, not in Hawaii.

On 7 December, Hawaiian time – 8 December in Asia – Japan simultaneously attacked Pearl Harbor, Malaya, Thailand, Hong Kong, the Philippines, Guam and Wake. The attack on the American fleet began without a declaration of war, which Roosevelt the next day called a day of infamy and which for years fixed in the United States an image of Japanese treachery. After the war the Tokyo tribunal found Tōjō guilty of, among other things, crimes against peace and sentenced him to death. Tōgō received twenty years’ imprisonment. Some writers later claimed that Roosevelt knew of the attack on Pearl Harbor and allowed it to happen, but historians reject this thesis on the basis of the documents: the intercepted messages showed that war was close, but not where the first blow would fall.

The phrase “Niitakayama nobore” itself entered Japanese and American memory of the war alongside the signal “Tora! Tora! Tora! (PL)”, with which the strike leader reported on the morning of 7 December that surprise had been achieved. The mountain whose name had served as the signal ceased to be Japanese four years later, when Taiwan returned to China after Japan’s surrender.