The Balkan Wars
The Balkan Wars marked the end of Ottoman rule in Southeastern Europe, and they involved several countries that would join the First World War just a few years later. A complicated alliance between Serbia, Montenegro, Bulgaria and Greece imploded over disagreement of the war spoils after defeating the Ottomans. This led to the 2nd Balkan War and also created much resentment that would play a role between 1914 and 1918 too.
Credit to : The Great War