The Potsdam Conference was the last of the wartime meetings of the Big Three. It lasted from 17 July to 2 August 1945. The three powers were represented by Joseph Stalin, Winston Churchill and, later, Clement Attlee and President Harry S. Truman. The agreements of the meeting included division of Germany and Austria into four occupation zones and issuance of a statement of aims of the occupation of Germany by the Allies: demilitarization, denazification, democratization, decentralization and decartelization. However, the most controversial part of matters dealt with the situation of Poland. The Big Three recognised the existence of the Communist-controlled Provisional Government of National Unity. In fact, it meant the end of recognition for the existing government-in-exile that resided in London. In addition, the provisional western border of Poland was defined by the Oder and Neisse rivers. In the end, the final border was officially settled only in 1990.