<Li> The Soviet zone of Germany and sector of Berlin . </Li> <Tr> <Td_colspan="2"> The four sectors of the Allied occupation of Berlin and exclaves . </Td> </Tr> <P> Upon the defeat of Nazi Germany in World War II, the victorious Allies asserted their joint authority and sovereignty over' Germany as a whole', defined as all territories of the former German Reich which lay west of the Oder--Neisse line, having declared the destruction of Nazi Germany at the death of Adolf Hitler (see 1945 Berlin Declaration). The four powers divided' Germany as a whole' into four occupation zones for administrative purposes, under the United States, United Kingdom, France and the Soviet Union respectively; creating what became collectively known as Allied - occupied Germany (German: Alliierten - besetztes Deutschland). This division was ratified at the Potsdam Conference (17 July to 2 August 1945). The four zones were as agreed in February 1945 by the United States, United Kingdom and Soviet Union meeting at the Yalta Conference; setting aside an earlier division into three zones (excluding France) proposed by the London Protocol . </P> <P> At Potsdam, the United States, United Kingdom and the Soviet Union approved the detachment from' Germany as a whole' of the German eastern territories east of the Oder--Neisse line; with the exact line of the boundary to be determined at a final German Peace Treaty . This treaty was expected to confirm the "shifting westward" of Poland's borders, as the United Kingdom and the United States committed themselves to support in any future peace treaty the permanent incorporation of former eastern German territories into Poland and the Soviet Union . From March 1945 to July 1945, these former eastern territories of Germany had been administered under Soviet military occupation authorities, but following the Potsdam Conference they were handed over to Soviet and Polish civilian administrations and ceased to constitute part of Allied - occupied Germany . </P>

Why did the allies occupy germany after ww2