After 1945, he took a leading role in establishing the Liberal Democratic Party of Germany (LDPD). He founded the Berlin branch of the LDPD in the summer of 1945 and acted as LDPD chairman from November 1945 after the first leader, Waldemar Koch, had been deposed by Soviet orders. On 17 March 1947, in a conference in Rothenburg ob der Tauber Külz and Theodor Heuss were elected co-chairmen of the planned Democratic Party of Germany (DPD), aimed at uniting liberals of both the Soviet and the Western occupation zones. The plans were never realised since Wilhelm Külz, unlike the East German CDU leader, Jakob Kaiser, participated in SED-dominated Deutscher Volkskongress (German People's Congress for Unity and True Peace) that took place on 6 December 1947. That brought about internal confrontations both within the LDPD as well as between the East and West German partners in the DPD. Although the LDPD leadership criticised that participation, it was unable to take any further steps demanded by the West German liberals. During a session of the united leadership of the DPD that took place on 18 January 1948 and Külz refused to attend, Heuss argued that the Liberal Democrats' unwillingness to take any measures against Külz proved their commitment to "the Russian conception of German unity". Arthur Lieutenant, the spokesman of the LDPD on the matter, declared that under those circumstances and considering reproaches laid against East German liberals, no further co-operation was possible. That was in fact the end of DPD. Together with Otto Nuschke (CDU) and Wilhelm Pieck (SED), Wilhelm Külz led the German People's Council (Deutscher Volksrat), forerunner of Volkskammer of GDR. From 1945 on, Külz was the publisher of the LDPD daily Der Morgen. In March 1948, Külz once again was the representative of the LDPD at the Deutscher Volkskongress, organized at the behest of the Soviet authorities and the SED. On the morning of 10 April 1948, Külz was found by his party deputy, Arthur Lieutenant, to have died in the night at his Berlin apartment, apparently from a heart attack. Legacy Although he was mostly unknown in West Germany and still is in Germany, Külz was viewed in East Germany as a prime example of a bourgeois but upright citizen who found his way to socialism. He was seen as one of the founding fathers of East Germany. Wilhelm-Külz-Stiftung, a foundation close to the Free Democratic Party,