Cecilienhof was the location of the Potsdam Conference between 17 July and 2 August 1945. The rooms had been largely refurnished to match the taste of the participants. Winston Churchill, later Clement Attlee, Joseph Stalin and Harry S. Truman met at the round table in the great hall. On 26 July 1945, Churchill and Truman issued the Potsdam Declaration defining the terms for Japanese surrender, while Truman had already given order to prepare the atomic bombing of Hiroshima and Nagasaki.
Following the July 26 Potsdam Declaration, where Allies outlined the terms of surrender for Japan and promised "inevitable and complete destruction" of Japan if they failed to comply, preparations were secretly under way to make use of the newly-tested Atomic Bomb. Here, the first nuclear device to be used as a weapon, codenamed "Little Boy", rests on a trailer cradle in a pit, ready for loading into the bomb bay of the "Enola Gay" in August of 1945.