After the collapse of Yugoslavia amidst German and Italian invasion in April 1941, the Axis puppet state which encompassed the entire Bosnia and Herzegovina, Independent State of Croatia (NDH) under the radical Croatian nationalist Ustaše regime was established. Bosnian Croats were divided, as some supported the NDH, some actively opposed it by joining or supporting the Yugoslav Partisans, while others chose to wait, not attracted either by fascist Ustaše or communist-led resistance. After the Ustaše campaign of genocide and terror, targeting Serbs, Jews, and Roma, a brutal civil war ensued. At the same time, a parallel genocide against Croats and Bosniaks was carried out by the Yugoslav Royalist and Serbian nationalist Chetniks. The Ustaše regime also persecuted any opponents or dissidents among Bosnian Croats, especially communists, pre-war members of the now-banned Croatian Peasant Party, and those connected with the partisan resistance. The Ustaše executed many Bosnian Croats, for instance, resistance fighters and supporters Jakov Dugandžić, Mostar's Ljubo Brešan and 19-year old Mostar gymnasium student Ante Zuanić, as well as a prominent Mostar CPP member Blaž Slišković (in Jasenovac concentration camp). Prominent Croat communist intellectual from Bosnia, Ognjen Prica, was shot by Ustaše in Kerestinec prison. Families of Bosnian Croats who left to join the partisan resistance were usually interned or sent to concentration camps by ustase authorities.