Armed resistance soon developed in the region, and by 1942, the Yugoslav Partisans controlled substantial territories, especially in mountainous parts of Slavonia. The Serbian royalist Chetniks, who carried out genocide against Croat civilian population, struggled to establish a significant presence in Slavonia throughout the war. Partisans led by Josip Broz Tito took full control of Slavonia in April 1945. After the war, the new Yugoslav government interned local Germans in camps in Slavonia, the largest of which were in Valpovo and Krndija, where many died of hunger and diseases.