In 1991 and early 1992 , approximately 18,000 Croatian citizens were missing or held by the JNA or its allies . Approximately 8,000 of these were imprisoned in internment camps in Serbia , Montenegro , Bosnia and Herzegovina , or in Croatian territory controlled by the JNA . The camps were set up in Begejci , Stajićevo , Sremska Mitrovica , Niš , Aleksinac , Manjača , Banja Luka , Knin , Bučje , Beli Manastir , Negoslavci , Vukovar and Morinj . Approximately 300 prisoners died while detained in the camps . Most of the prisoners had been released by August 1992 . 1,703 were people still missing as a result of the 1991 campaign . Both sides committed numerous atrocities during the conflict . The most significant one committed by Croatian forces was the Gospić massacre . The atrocities committed by Serb forces were far greater in scale . The most significant ones were those committed in Kijevo , the killing of more than 200 prisoners of war in the aftermath of the Battle of Vukovar , and the bombardment of Dubrovnik . Those war crimes were subsequently prosecuted by the International Criminal Tribunal for the former Yugoslavia , which was set up in 1993 under the terms of UN Security Council Resolution 827
Gospić massacre
Gospić massacre
1991 Yugoslav campaign in Croatia