 Complete the following phrase:  Serbia fought in the Balkan Wars of 191213, which forced the Ottomans out of the Balkans and doubled the territory and population of the Kingdom of Serbia. In 1914, a young Bosnian Serb student named Gavrilo Princip assassinated Archduke Franz Ferdid of Austria, which directly contributed to the outbreak of World War I. In the fighting that ensued, Serbia was invaded by Austria-Hungary. Despite being outnumbered, the Serbs defeated the Austro-Hungarians at the Battle of Cer, which marked the first Allied victory over the Central Powers in the war. Further victories at the battles of Kolubara and the 