>>509419198It's hard to judge how well Serbians fought and how much of it was just rest of the factors.
A-H had a hodge-podge army that completely lacked cohesion fighting a war of aggression, Serbia on the other hand could rely on mountaineous terrain and patriotism defending your homeland.
It's obvious that Serbia could have stood its ground out 1 on 1, but it's not because Serbians were military geniouses.