War ended in May 1945 and his father was released from a period as an American prisoner of war in 1946. The family moved to Neustrelitz, a small town in the northern part of what was by now being administered as the Soviet occupation zone. The elder Popp helped set up the Neustrelitz branch of the &lt;a href="Socialist%20Unity%20Party%20of%20Germany"&gt;Socialist Unity Party ("Sozialistische Einheitspartei Deutschlands" / SED)&lt;/a&gt;, established under contentious circumstances in the Soviet zone in April 1946. During this period the family secretly gave sanctuary to an SPD activist who had been released from a concentration camp and now faced detention by the Soviet occupation authorities in the context of Stalin's purges against non-Communist activists. The matter did not end well. Both the SPD activist and Popp's father were arrested by the Soviet authorities. After his father had been released from jail, in 1950 the family moved again, this time back to what was becoming known as West Berlin, as the military division of the city was increasingly reflected by administrative, political and, later, physical divisions. By 1956 Dieter Popp's father had died. In West Germany and West Berlin the old Communist Party had not been subsumed into the SED, but it had become increasingly marginalised, seen both by the West German political establishment and the population more generally as nothing more than a proxy for the foreign policy of the Soviet Union. In August 1956 the Communist Party was banned by the West German Constitutional Court. Popp, by now aged 18, could not understand why "in the west the Communist Party was banned and Communists were again being persecuted".