The Japanese attack on Pearl Harbor on December 7 1941 remains etched in public memory as the turning point of WW2. But in fact, it was Hitler’s declaration of war on the United States – four days later on December 11, 1941 – that changed everything.

In this episode, Professor of International Relations at Cambridge University Brendan Simms tells Dan the story of those five unsettling days. Churchill did not sleep “the sleep of the saved and thankful” after the attack, as he later claimed. Japan’s leaders were unsure whether Hitler would honour a private commitment to declare war. Roosevelt knew that many Americans didn’t want their country to entangle itself in a conflict with the Third Reich as well as Japan. In the end, it was Hitler’s decision that ended the uncertainty, bringing the US into the European war and transforming world history. You can read more in 'Hitler's American Gamble' by Brendan Simms and Charlie Laderman.

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