Following the Invasion of Yugoslavia in April 1941 , the Axis powers occupied the entire territory of the Kingdom of Yugoslavia and established a puppet state , the so-called Independent State of Croatia ( NDH ) on the territory of present-day Bosnia and Herzegovina and Croatia . The Ustaše government saw Serbs , Jews , Romanis and antifascist Croats as a disruptive element and enemies of the Croatian people , and immediately started with their prosecution . Upon the establishment of the NDH , Ustaše officials immediately began making harsh statements against the Serbs . Although some of the prominent Serbs first offered cooperation to the new Ustaše government , Serbs were outlawed . During the first months of NDH 's existence , numerous legal decisions were made against the Serbs : they had to leave the public service , had to move to the northern parts of Zagreb , could walk through Zagreb only during the day , had to wear a badge with the letter " P " ( stood for " Pravoslavni " , meaning Orthodox Christians ) , the name of their faith was changed from Serbian Orthodox to Greek-Eastern , and usage of the Cyrillic script was prohibited . Ustaše were making lists of Serbs which they used for deportations to Serbia . About 175,000 Serbs were deported from NDH to Serbia during the first two years of NDH 's existence . Many historians and authors describe the Ustaše regime 's mass killings of Serbs as meeting the definition of genocide , including the present-day Croatian and Bosnian high officials , Yad Vashem the Holocaust memorial center and Raphael Lemkin who is known for coining the word '' genocide '' and initiating the Genocide Convention . Sisak and Jastrebarsko concentration camp were specially formed for children . Diana Budisavljević , a humanitarian of Austrian descent , carried out rescue operations and saved more than 15,000 children from Ustashe camps
mass killings of Serbs
Persecution of Serbs in the Independent State of Croatia
Serbs of Croatia