The state of Yugoslavia was established in 1919 at the Paris Peace Conference that occurred following the First World War. The new state was made up of Serbia, Montenegro, and former provinces of Austria-Hungary: Bosnia-Herzegovina, Croatia, and Slovenia. From 1920-1929, it was known as the Kingdom of Serbs, Croats and Slovenes.
During the interwar period (1919-1939) Serbian monarchs (King Peter I [1920-1929] and King Alexander I [1929-1941]) kept the ethnic rivalries in check and provided an era of relative stability. During the Second World War, Yugoslavia attempted to remain neutral. However, after Italy and Germany exerted considerable diplomatic pressure and issued threats of force, Yugoslavia's regent, Crown Prince Paul, reluctantly joined the Axis alliance (Germany and Italy) on 25 March 1941. Two days later, on 27 March 1941, anti-German officers in the Yugoslav army overthrew Prince Paul and rejected the Axis alliance. German forces invaded Yugoslavia on 6 April 1941, and, by 17 April, Yugoslavia was under German occupation.
During the Second World War, the Communist leader, Marshal Tito (Josip Broz), led Yugoslav resistance to the Germans. After almost four years of guerrilla warfare, Tito's forces liberated Yugoslavia and established a Communist regime. Tito ruled Yugoslavia with an iron hand, and no ethnic violence occurred during his rule. When Tito died in 1980, the Yugoslav Communist party formed a ruling committee. The presidency would rotate annually between the Communist leaders of the six provinces (Serbia, Croatia, Slovenia, Macedonia, Montenegro, and Bosnia-Herzegovina).
Increasing pressure for democratization developed in Yugoslavia during the 1980s. In 1989, the Communist government bowed to popular pressure and established a multi-party system. Chaos soon followed. In 1991, violence erupted in Yugoslavia as various ethnic groups utilized the democratic reforms to secede from Yugoslavia. Savage fighting broke out as different ethnic groups advanced territorial claims, and the Serbian majority in Yugoslavia struggled to maintain its power. The result was a very unique type of warfare that one historian aptly described thusly:
For most of the period between 1992-95, the Yugoslav wars of succession were waged by amateurs. When the JNA [People's Yugoslav Army] was removed from the equation [through ethnic disintegration], they took with them the normal codes of conduct held by modern professional military officers. Rival militias fired weapons in the vicinity of opposing troops, more often than not, intent on killing civilians. The result was to create a pattern of combat where military casualties were few. The new armies knew how to kill, but not how to wage war against other soldiers properly. Unprotected civilians were a different matter. And so, the objective in these wars was not to defeat the opponent's combat power but to consolidate new ethnic nation-states by killing or driving out those who did not fit.
The dissolution of Yugoslavia has led to the involvement of several international peacekeeping missions established by the European Community, the United Nations, and the North Atlantic Treaty Organization.