Good stamp. The territory of Croatia, Bosnia and Herzegovina and the region of Syrmia became a puppet state of Nazi Germany called the Independent State of Croatia. Istria, the port city of Rijeka, and a portion of Dalmatia up to Split were occupied by Italy. Baranja and Medjumurje were occupied by Hungary. Although the recently returned exiled Ustashe was in charge of the new regime, the Axis occupiers initially offered the state leadership to Vladko Maček, the leader of the Croatian Peasants' Party (HSS), but he refused. Only one day after entering Zagreb, on April 17, 1941, Ante Pavelić proclaimed that all people who offended, or tried to offend against the Croatian nation were guilty of treason — a crime punishable by death. The Ustashe regime introduced anti-Semitic Nuremberg-style laws, and also conducted massacres of mostly Serbs and other non-Croats, as well as running concentration camps such as the one at Jasenovac and Stara Gradiska where opponents of the Ustashe regime and other 'undesirables' were held. The Ustase murdered Serbs, Jews, Roma, as well as Croats who opposed Ustase rule.