The driving force in the Balkans is still nationalism, not religion. Serbs have fought Catholic Croats was well as Muslim Bosnians and Kosovars. The claim that Serbia is fighting Islamic terrorism is window dressing. Serbia wants every canton with a majority of Serbians to be part of Serbia. Fine. That implies allowing the rest of Kosovo to got its own way, and allowing Croat cantons to join Croatia, and so forth. They haven’t allowed that.
The Austrians dangled the Archduke (whom they didn't even like) on a purposely important Serbian holiday to provoke them and didn't supply him with protection (even though they had some of their army stationed in Sarajevo and had control of the Bosnian Muslim soldiers.)
The assassination team was mostly teenagers and included a Muslim. When one of them threw a grenade at his motorcade, they still didn't beef up security.
His car stopped 5 feet from Gavrilo Princip - which appeared the only way the inept, bumbling crew could do the job.
Once accomplished there were suddenly the thousands of soldiers and police on the streets to arrest him and then begin the hangings of civilian Serbs (including women) all around the locations where the Austrian army was stationed in Bosnia.
The Austrians wanted an excuse and German especially was keen on pushing them into a war and subsequently getting a jump on a war with Russia.
Not sure how to be polite and still say that's utter crap.
Nationalism is steeped in a culture for a long time, and always emerges when it has an opportunity. German nationalism was hatched from an egg, that sense of German superiority and entitlement pre-dated Nazi Germany by centuries.
Serbia had a multitude of opportunities in the last 100 years to drive out all the Muslims (Bosnian and Albanians, both)in the Balkan wars and take what they wanted of Yugoslavia -- especially post-WWI. If they had, Croatia would have never had Dalmatia or the Krajina, and would have been confined to a small dot on the map. Serbia did none of that, but instead chose to share. That was their mistake. Because by the time, Tito came along, he made sure that Serbia stayed weak and small so that he could be the only glue holding Yugoslavia together.
If Serbs had been the raving nationalists you claim, they wouldn't be where they are today. The difference is that Croats, Bosnian Muslims and Albanians can all be hardcore nationalists and get called "freedom fighters" for it. Serbs, on the other hand, get called "hardcore nationalists" just for trying to preserve their sovereign borders and not cave in to globalist attempts to ravage them..
What the hell are you talking about? Cantons? What cantons? Before you start shooting your mouth off, learn a thing or two about the history of the region. "Kosovars" don't exist -- much like "Palestinians." It isn't a nation, a people. There are Serbs (indigenous) and there are Albanians (illegal aliens / occupiers).
Regarding the fighting, the Serbs were only trying to defend themselves (learning a thing or two the hard way in 1941/2) and trying to prevent the sequel to WWII (which never really ended in Yugoslavia).