@Sataraš first sentence doesn’t make much sense, but anyway, Austria-Hungary attacked Serbia, not other way around. Citizen of AH Empire killed the heir to the throne of that same Empire, in that same Empire. So most logical next step is to attack a neighbouring country? Bosnia was f*cked up during Ottoman times, when Austria took over and started settling people there, they brought some basic stuff there for the first time (like carrot, potato, pears… I won’t even mention technology), so in that short period who ever took over Bosnia could have just make it better and more developed, Ottoman made sure it couldn’t be worse. That was time of romantic ideas for most of Europe including Slavic world, especially those in Dungeon of Nations. Slavs looked up to their free brothers in those times, so union with Serbia would be greeted as it was at the end of the war.