In 1941, Syrmia was occupied by the World War II Axis powers and its entire territory was ceded to the Independent State of Croatia, a Nazi puppet state. The fascist Ustashe regime systematically murdered Serbs (as part of the Genocide of the Serbs), Jews (The Holocaust), Roma (The Porajmos), and some political dissidents. In August 1942, following the joint military anti-partisan operation in the Syrmia by the Ustashe and German Wehrmacht, it turned into a massacre by the Ustasha militia that left up to 7,000 Serbs dead. Among those killed was the prominent painter Sava Šumanović, who was arrested along with 150 residents of Šid. In 1945, with the creation of new borders, eastern Syrmia became part of the People's Republic of Serbia, while western Syrmia became part of the People's Republic of Croatia.