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Centre for Geopolitics

Providing historically-grounded solutions to enduring geopolitical problems

On Saturday, 28th of September, the Forum on Geopolitics hosted a high-level conference on the US entry into World War II at Peterhouse College, Cambridge. Its focus was a new book project by Professor Brendan Simms (Cambridge) and Charlie Ladermann (King’s College London) on the five days between the Japan’s 1941 attack of Pearl Harbour and Hitler’s declaration of war on the US. This short span of time represents a fascinating period in the study of diplomatic history as it constitutes a moment when the US found themselves in the ‘wrong war’. After all, US president Roosevelt had wanted to join World War II actively, but only in the Atlantic – against Germany. After Pearl Harbour, however, it looked like the war the US would fight was to be in the Pacific, against Japan. Only Hitler’s declaration of war on the 11th of December 1941 resolved this dilemma for the Roosevelt administration, as now Washington could legitimately join both the Atlantic and Pacific theatre of war. With a delay of five days, a European conflict had truly transformed into another World War.

What, then, were the internal deliberations of the US government in this short period of five days when Roosevelt and his key advisors tried to shape the new situation to their own requirements? And how did events unfold over these five days, culminating into all-out war between the US on the one hand and Germany and Japan on the other? To answer this question, the conference brought together researchers from three continents (America, Europe, Asia) to comprehensively cover the considerations and actions of key players such as the US, Germany and Japan.  Moreover, it addressed the role of other key actors such as Italy, the United Kingdom and the Soviet Union.

At the centre of the event were keynotes by two eminent speakers, Prof. Gerhard Weinberg, Professor Emeritus of History at the University of North Carolina at Chapel Hill and author of A World at Arms : A Global History of World War II, and Prof. Evan Mawdsley, former Professor of International History at the University of Glasgow and author of December 1941: Twelve days that began a World War. Their contribution as well as that of all panellists has helped to significantly broaden our understanding of how statesmen react to outside events beyond their immediate influence, and how World War II turned from a regional into a global conflict.