Many Serbs themselves took up arms and joined the Chetniks, a Serb nationalist movement with the aim of establishing an ethnically homogeneous 'Greater Serbian' state within the Kingdom of Yugoslavia. The Chetniks, in turn, pursued a genocidal campaign against ethnic Muslims and Croats, as well as persecuting a large number of communist Serbs and other Communist sympathizers, with the Muslim populations of Bosnia, Herzegovina and Sandžak being a primary target. Once captured, Muslim villagers were systematically massacred by the Chetniks. Of the 75,000 Muslims who lost their lives in Bosnia and Herzegovina during the war, approximately 30,000 (mostly civilians) were killed by the Chetniks. Massacres against Croats were smaller in scale but similar in action. Between 64,000 and 79,000 Bosnian Croats were killed between April 1941 to May 1945. Of these, about 18,000 were killed by the Chetniks.