Herzegovina). In early 1943 Partisans took steps to establish ZAVNOH (National Anti-Fascist Council of the People's Liberation of Croatia) to act as a parliamentary body for all of Croatia – the only one of its kind in occupied Europe. ZAVNOH held three plenary sessions during the war in areas which remained surrounded by Axis troops. At its fourth and last session, held on 24–25 July 1945 in Zagreb, ZAVNOH proclaimed itself as the Croatian Parliament or Sabor. By the end of 1941 in the territory of the NDH, Serbs comprised approximately one-third of the population but about 95% of all Partisans. This numerical dominance lessened later, but until 1943 Serbs formed a majority of Partisans in Croatia (including Dalmatia). Territories in Croatia proper with a substantial number of Serb inhabitants (Lika, Banija, Kordun) formed the most important source of manpower for the Partisans. In May 1941 the Ustasha regime ceded northern Dalmatia to Fascist Italy, which caused increasingly massive support for the Partisans among the Croats of Dalmatia. In other parts of Croatia Croat support toward the Partisans gradually increased due to Ustasha and Axis violence and misrule, but much more slowly than in Dalmatia. There were only 1,492 Partisans from Serbia out of the 22,148 Partisans of Tito's Main Operational Group at the Battle of the River Sutjeska in June 1943, and 8,925 were from Croatia (of which 5,195 were from Dalmatia), but in ethnic terms, 11,851 were Serbs against 5,220 Croats. At the end of 1943 all 13 Dalmatian Partisan brigades had a Croat majority, but among the 25 Partisan brigades from Croatian proper (without Dalmatia) only 7 had a Croat majority (17 had a Serb majority and one had a Czech majority). According to historians Tvrtko Jakovina and Davor Marijan the main reason for massive participation of Croats in Battle of the Sutjeska in June 1943 was ongoing terror of Italian fascists. According to Tito, one-quarter of Zagreb's population (i.e. more than 50,000 citizens) participated in the Partisan struggle during which over 20,000 of them were killed (half of them as active fighters). As Partisan combatants 4,709 citizens of Zagreb were killed while 15,129 were killed in Ustasha and Nazi prisons and concentration camps, and another 6,500 were killed during anti-insurgency operations. In the final offensive for the liberation of Yugoslavia, from Croatia was engaged 165,000 soldiers mostly for the liberation of Croatia. On Croatian territory after