This pamphlet continues our series of publications devoted to conditions in Japan in the period of the Taisho Emperor who reigned from 1912 to 1926. Taisho Studies have tended to be neglected because it was a comparatively short reign and because the Emperor had to pass his duties to a regent because of his illness at the end of this period. But it was a time when Japanese strained every muscle in order to build on the prestige she had acquired through defeating Russia in the war of 1904-5. During the Great War she had considerable success both industrially and financially and secured her position internationally through her presence at the Paris Peace Conference. But her success generated suspicion on the part of other countries, even her long-term ally, Britain. In 1914 Britain found herself in a global war and had to cope with the security problems of a far-flung empire. She was in difficulties over meeting the cost of sustaining naval forces in the Pacific and Indian Oceans at their accustomed levels and felt she had no alternative but to withdraw these forces to Europe in order to deal with the growing German naval power. Britain made many appeals to Japan for help. But until December 1916 these were politely refused. This paper deals with the Tokyo cabinet’s decision to send a destroyer squadron to the Mediterranean in order to defend allied convoys carrying food and troops to European battle fronts from German U boat attack. Though small in scope compared to Japan’s role in the Pacific, it made a timely contribution to Britain’s current dilemma. This event has tended to go unnoticed because Japan’s contribution to World War I has tended to be devalued in international literature written since 1945.