Impossible, considering that only 500,000 Serbs died from all fighting in WW2.
Postwar Yugoslavia estimated the number to be 700,000. However, the number I quoted appears to be on the higher end of the estimates - the Simon Wisenthal Center estimated 500,000 which is probably the number that I will use in the future to avoid controversy. Either way many Serbian civilians were killed in death camps by the Ustase during WWII and that is why Serb civilians were ready to fight, die and kill rather than end up under Croatian rule again. Here is the link to Wikipedia article which discusses the widely varying estimates of the number of dead which range from 30,000 (very low) to 1 million (very high). http://en.wikipedia.org/wiki/Usta%C5%A1e#World_War_II