The Kosovo War was an armed conflict in Kosovo that lasted from 5 March 1998 until 11 June 1999. ... The war ended with the Kumanovo Treaty, with Yugoslav and Serb forces agreeing to withdraw from Kosovo to make way for an international presence.Kosovo conflict. Kosovo conflict, conflict (1998–99) in which ethnic Albanians opposed ethnic Serbs and the government of Yugoslavia (the rump of the former federal state, comprising the republics of Serbia and Montenegro) in Kosovo. ... An ethnic Albanian family returning to Kosovo from a refugee camp, 1999.