British–Japanese agreement on the German islands

On 16 February 1917 the British ambassador in Tokyo, Sir Conyngham Greene, informed the Japanese foreign minister, Viscount Ichirō Motono, that Britain would support Japan’s claims to the German possessions north of the equator if Japan supported similar British claims south of the equator. It was a secret agreement, of which the public learned only two years later. The Japanese reply is dated 21 February. The British chronology of the war records the matter under 14 February, and Ernest Scott’s Australian official history writes of an exchange of notes on 17 February. The decision was thus taken in London in the middle of the month and formally confirmed over the following week.

Destroyers for islands

From the beginning of the war Japan had refused to send warships to Europe. When in February 1916 the British asked for Japanese destroyers, Tokyo agreed only to patrols in the Indian Ocean. The situation changed at the end of 1916. The new government of Marshal Masatake Terauchi, in which foreign affairs were directed by Motono, was ready to help, but wanted something in return. According to Japanese studies, on 11 January 1917 London asked for warships to escort transports in the Mediterranean, where German and Austro-Hungarian submarines were sinking more and more ships.

On 27 January Motono told Greene that the imperial government would like an assurance that at the future peace conference Britain would support Japan’s claims to the German rights in the province of Shantung, that is above all to the Kiautschou leasehold with the port of Tsingtao, taken by the Japanese in 1914, and to the German islands in the Pacific north of the equator: the Marianas, the Carolines and the Marshall Islands. Tokyo had long made clear it would not give them up. Four days later Germany announced unrestricted submarine warfare, and every escort vessel became worth its weight in gold to the British. The prime minister, David Lloyd George, explained in Paris in 1919 that the submarine campaign had been very dangerous at the time, there was a shortage of destroyers in the Mediterranean, and Japanese help was urgently needed. “We were in a tight corner and we agreed,” he said.

A question for Australia

Before replying, London asked the opinion of the dominions to which the German islands south of the equator had fallen. On 1 February the British government asked the Australian prime minister, Billy Hughes, whether he had any objection to a promise to Japan. The choice had seemed settled since December 1914, when London halted the Australian expedition to the northern islands. Hughes replied on 7 February that Australia would not oppose Japanese occupation of the islands north of the equator, with the exception of one or two small islands on the border, such as Nauru and Ocean Island, that is Banaba. Both these phosphate-rich islands, however, lay south of the equator. Scott describes with irony how the Colonial Office, having looked at a map before replying, politely asked on 8 February which islands north of the equator were actually meant. Hughes admitted the next day that Nauru and Ocean Island lay slightly south of the equator, and that he did not know the names of any islands just north of it.

The terms of the agreement

In a letter of 16 February Greene passed on to Motono a message from the British government. Britain “with pleasure” acceded to the request for an assurance that at the peace conference it would support Japan’s claims to the German rights in Shantung and to the German possessions in the islands north of the equator, “on the understanding” that in the eventual peace settlement Japan would treat “in the same spirit” British claims to the German islands south of the equator. These were mainly the lands occupied in 1914 by the Australians and New Zealanders: German New Guinea with the Bismarck Archipelago, Nauru and Samoa.

On 21 February Motono replied that the Japanese government deeply appreciated the friendly spirit of the British assurance and saw in it fresh proof of the close ties uniting the two allied powers. For its part it was fully prepared to support in the same spirit the claims which Britain might put forward at the peace conference to the German possessions south of the equator. At the same time the Japanese were holding similar talks with other allies. On 19 February Motono handed a memorandum on the subject to the ambassadors of France and Russia. Russia agreed the very next day, and France on 1 March, on condition that Japan persuade China to break off relations with Germany. Italy gave its assurance later, orally, in Rome.

The Japanese squadron

The Japanese kept their side of the bargain. On 10 February the navy formed the 2nd Special Squadron, consisting of the cruiser Akashi and eight destroyers of the 10th and 11th Destroyer Divisions, under Rear-Admiral Kōzō Satō. The ships sailed via Colombo and Port Said and on 13 April reached Malta, the main base of the British Mediterranean Fleet. By the end of the war they had made several hundred escort voyages, protecting transports carrying troops and supplies. Two other Japanese cruisers were sent to Cape Town at this time.

The agreement remained secret until the end of the war. Its content came to light only during the peace negotiations, and in April 1919 the texts of the notes of February 1917 were reprinted in the American press. At the Paris Peace Conference Japan was able to invoke it. The Treaty of Versailles awarded it the German rights in Shantung, and the islands north of the equator became a League of Nations mandate administered by Tokyo. China, which had itself entered the war on the side of the Entente, regarded this as a betrayal. The decision on Shantung provoked protests in Peking which gave rise to the May Fourth Movement, and the Chinese delegation did not sign the treaty.