As the centuries passed, resistance to domination by foreign empires and mistrust between Slavic groups increased. In 1914, Serb hostilities against the ruling Austro-Hungarian Empire resulted in the assassination of the heir to the Austrian throne, Archduke Ferdinand. A month later, Austria-Hungary declared war on Serbia, starting World War I.

When the Austro-Hungarian Empire was finally defeated in 1918 at the end of the war, the new country of the Kingdom of the Serbs, Croats, and Slovenes was formed, unifying the Slavic people. However, the new country was plagued with economic problems as a result of the war and experienced continued tension between the peoples of its various republics. In particular, Serbs and Croats vied for control of the nation. According to international studies professor Sabrina Petra Ramet, "Yugoslavia was created by Serbian bayonets" and was dominated by Serbs for most of its history.

In 1929, Serbian king...