on a 1941 directive, was the creation of an ethnically homogeneous Greater Serbia. The largest Chetnik massacres took place in eastern Bosnia within the NDH where they preceded any significant Ustashe operations. In the territories they controlled, Chetniks committed genocide against the Croat and Muslim civilian populations. However, they also collaborated with some of the Ustashe forces in northern Bosnia and they fought together against the Yugoslav Partisans during the Case White. A certain change in relations towards Serbs in NDH took place in the spring of 1942 on German demand, as the Germans realized that the Ustaše policy towards Serbs strengthened their rebellion, which was putting pressure on the German army that had to send more of its troops to the NDH territory. Afterwards, Ustaše founded the Croatian Orthodox Church and Serbs were recruited to the Croatian Home Guard units. Ustaše stopped with deportations of Serbs and their forced conversions to Catholicism. However, these measures did not significantly affect the Serb rebellion. The establishment of the Church was done in order to try and pacify the state as well as to Croatisize the remaining Serb population once the Ustaše realized that the complete eradication of Serbs in the NDH was unattainable. Persecution of Serbs continued however, but was less intense. At the beginning of 1942, NDH authorities started making agreements with the Chetniks to avoid conflicts and coordinate actions against the Yugoslav Partisans. On 8 May 1945, Yugoslav Partisans entered Zagreb, which marked the collapse of the Ustaše regime and the liberation of Croatia from the Nazi occupation. Following the end of the war, Croatia entered union with Bosnia and Herzegovina, Macedonia, Montenegro, Serbia, and Slovenia and formed the Socialist Federal Republic of Yugoslavia. Socialist Yugoslavia During the Second World War, at the Second and Third sessions of the National Anti-Fascist Council of the Peoples Liberation of Croatia (ZAVNOH) held in October 1943 and May 1944 respectively, the equality of the Serbian and Croatian nations, as constituent nations of the federal unit of Croatia, was recognized in every aspect. Later, in 1963, the Croatian Constitution did not mention the Serbs in Croatia as a constituent nation of SR Croatia. Constitution of 1974 defined Croatia as a "national state of Croatian people, state of Serbian people in Croatia and state of other nationalities that live in it". On 22 December 1990, HDZ government of Franjo Tuđman promulgated a new Croatian