One of the most important resolutions of the Potsdam conference was the definition of the borders defined in Eastern Europe. The conference agreed to hand over to the USSR the city of Konigsberg with the surrounding region. After long discussions, the new border between Poland and Germany has been defined: along the road from the Oder to Westneia. Poland also received the city of Gdansk and most of East Prussia. The border of Poland became the Oder and the Neisse to the west, and the country received part of the former East Prussia. This required that millions of Germans be transferred to Germany in these regions. The Romanian, Hungarian and Bulgarian governments were already controlled by the Communists and Stalin stubbornly refused to let the Allies intervene in Eastern Europe. While in Potsdam, Truman Stalin spoke of the “new weapon” of the United States (the atomic bomb) that she wanted to use against Japan. On 26 July, the conference issued an ultimatum to Japan, which called for an unconditional surrender and, if not, threatened to launch more serious airstrikes. After Japan rejected this ultimatum, the United States dropped atomic bombs on Hiroshima and Nagasaki. When Truman informed Stalin of the atomic bomb, he stated that the United States had “a new weapon of unusual destructive force”, but that Stalin had full pity for the development of the atomic bomb from Soviet spy networks in the Manhattan Project and he told Truman at the conference that he hoped Truman would “use it well against the Japanese.”  The Soviet Union presented to the Conference a proposal on the territories related to the mandate, which corresponded to the objectives set at the Yalta Conference and the United Nations Charter.
The Potsdam conference took place in Potsdam from 17 July to 2 August 1945. (In some older documents, it is also called the Berlin Conference of the three heads of government of the USSR, the United States and the United Kingdom.   Participants were the Soviet Union, the United Kingdom and the United States, represented by Prime Minister Joseph Stalin, Prime Minister Winston Churchill and Clement Attlee and President Harry S. Truman. They met to decide how to manage Germany, which nine weeks earlier, on 8 May (Victory Day in Europe), had declared itself ready to surrender unconditionally. Among the objectives of the conference were the establishment of the post-war order, the issues of the peace treaty and the fight against the effects of war. The official communication on the restart of the meeting indicated that the conference had “strengthened ties between the three governments and broadened the framework of their cooperation and mutual understanding.” It was stated that the governments and nations of the three states – the members of the conference “with other UNITED nations will ensure a just and lasting peace.” The delegations were led by I. V.
Stalin, U.S. President H. Truman and British Prime Minister W. Churchill (from 28 July he was replaced by a new Prime Minister, Mr.C. Attlee). He also attended the conference Foreign Minister of the USSR and Great Britain V.M Molotov and A. Eden, Secretary of State of the United States, J. Byrnes, Secretary of the British Cabinet Minister Secretary A.
Bridges, Chief of Staff of the USSR A. I. Antonov, Chief of The United States G. Collaborators.