[sofixa]

> World War 1 ended up with Brits and Germans killing each other because a Bosnian Serb assassinated an Austro-Hungarian Royal

Russians and French died in much higher numbers on the Entente side than the Brits (who only joined due to Belgium's neutrality being violated anyways).

However, you probably know that the assassination of the morganatically married heir presumptive of the Austro-Hungarian throne was not the real reason for the war, only the spark that ignited the powder keg. There were many reasons and a lot of tension building for decades, starting with, funnily, Germany beating Austria which forced them to expand south, towards Bosnia, and also Germany beating France making the latter want revenge. The former pitted Austria-Hungary against Russia in the Balkans, on top of the many problems between the different Balkan countries. The latter made France eager for revenge and desperate to not be alone next time, hence it's cozying to Russia and the UK. Sprinkle an agressive German naval build-up that pushed the UK towards the Entente, German fears of Russian rearmament, Austrian fears of irrelevance, etc. and you have a powder keg with clearly defined lines just waiting for a spark.