In April 1941 Nazi Germany created a puppet state in occupied Yugoslavia called the Independent State of Croatia. Within weeks its leaders — a fascist movement called the Ustaše — had begun one of the most savage campaigns of ethnic extermination of the entire WWII era. They murdered between 300,000 and 700,000 Serbs, Jews, and Roma in four years. Their methods were so brutal that even senior Nazi SS officers filed formal complaints about the violence. This is the genocide almost nobody talks about. The Independent State of Croatia — known by its Croatian initials NDH — was established on April 10, 1941 following the Nazi invasion of Yugoslavia. It was led by Ante Pavelić, a fascist lawyer who had spent years in exile in Italy and Hungary preparing for this moment. The NDH immediately passed racial laws modeled on the Nuremberg Laws targeting Serbs, Jews, and Roma. Its stated goal was a ethnically pure Croatian state — to be achieved through conversion, expulsion, or extermination.