First of all, let's use correct labels.
These Croatian soldiers weren't necessarily Nazis any more than the average rank and file WWII German soldier was a Nazi.
Additionally, these "anti-fascists" were most probably the pro-Communist irregulars loyal to Tito.
These Croats were probably fighting to defend their country from a Communist takeover, not to defend their government's cowardly collaboration with the Nazis.
Don't buy the left's rhetoric hook, line and sinker.