After the German invasion of Yugoslavia in April 1941, the country was divided between Germany and its allies, Italy, Bulgaria, and Hungary.
The regions of Croatia (not including the Adriatic coast which is today part of Croatia) and of Bosnia and Herzegovina were united into a puppet state – the so-called Independent State of Croatia - that was ruled by the Croatian fascist Ustaša movement. The Ustaša immediately embarked on a campaign "to purge Croatia of foreign elements". Hundreds of thousands of Serbs were expelled or sadistically murdered in camps established by the Ustaša. The concentration of Jews in camps began in June 1941. By the end of that year about two thirds of Croatia's Jews had been sent to Ustaša camps, where most of them were killed on arrival. In August 1942 and May 1943 the Germans deported the remaining Jews from Croatia to Auschwitz. 30,000 out of Croatia’s 37,000 Jews perished in the Holocaust.