At Šabac in Dulag 183, a German transit camp for POWs in World War II Serbia, which opened in September 1941 (and closed in September 1944), Partisan POWs and members of their families were held. It is estimated that more than 5,000 persons were executed, not counting Jews and Roma people. "Central European Jewish refugees, mostly Austrians, were shot by troops of predominantly Austrian origin in retaliation for casualties inflicted by Serbian partisans on the German Army". The orders issued by Field Marshal Wilhelm Keitel in September 1941 called for the German Army to shoot 100 Serbs for every German soldier killed by the Serb guerrillas and did not call for Jews to be singled out. Due to rampant anti-Semitism in the German officer corps, Serbian Jews were scapegoated and targeted for mass retaliatory shootings. German historian Jürgen Förster, a leading expert on the subject of Wehrmacht war crimes, argued the Wehrmacht played a key role in the Holocaust and it is wrong to ascribe the Shoah as solely the work of the SS while the Wehrmacht were a more or less passive and disapproving bystander.