The creation of the new state was supported by pan-Slavic and Serbian nationalists. The pan-Slavic movement wanted to see all South Slavs united into a single state, while for the Serbian nationalists the desired goal of uniting the majority of the Serb people across Southeastern Europe into one state was also achieved. Furthermore, as Serbia already had a government, military and police force it was the logical choice to form a nucleus of a new Yugoslav state.
The formation of a new constitution in 1921 sparked tensions between the different Yugoslav nationalities, and over time hostilities grew towards the government, which many saw as biased towards the Serbs. The largest ethnic group was the Serbs, followed by the Croats, Slovenians, Bosnian Muslims, Macedonians and Albanians.
Opposing the Nazis and their local allies were the Communist partisans, led by Tito, pictured here at the entrance to his mountain hideout, shortly before the German attack
Credit: Imperial War Museum
Tensions were particularly fraught between Serbs and Croats, while other conflicts existed between Serbs and Macedonians, especially because the official position of the Yugoslav Government was that the latter were ethnic Serbs, which of course they disagreed with.
With ethnic and religious hostilities not far from the surface, Regent Prince Paul signed the tripartite pact on 25 March 1941, promising cooperation with the Axis powers in the hope of staving off a full-on invasion. Massive anti-Axis demonstrations erupted in Belgrade. On 27 March the regime of Prince Paul was overthrown by a military coup with British support. Seventeen-year-old Peter II was declared the new leader and the country withdrew its support from the Axis, which led to the Axis powers invading on 6 April and quickly conquering it.
During the Second World War, these ethnic divisions became so inflamed that many Yugoslavs were more interested in killing each other than killing German occupiers. Croats massacred Serbs in the name of Catholicism, Serbs torched Muslim villages for the Orthodox and Monarchist Chetniks fought pitched battles against Communist partisans. Added to this mix were the Italians and Germans, who themselves killed thousands of people, with the Germans executing entire towns in retaliation for partisan attacks.
Out of this mixture of violent rivalries emerged the Ustache, far-right Croat nationalists who sided with the Nazis and who killed hundreds of thousands of Serbs during the course of the war. Opposing them were the Communist partisans, led by Tito. They were composed of men, women and children of all ethnic backgrounds, though the majority were Serbs.
The Axis mounted a series of offensives against the partisans, but none achieved their goal of destroying its leadership and fighting ability. In fact, it had the opposite effect, as each failed attack only increased the credibility of the partisans, swelled their numbers and encouraged support from the Allies, especially the British. The partisans would become the nucleus of the post-war Yugoslav state.