The Breakup of Yugoslavia occurred between 25 June 1991 and 27 April 1992, when the Socialist Federal Republic of Yugoslavia's constituent republics split apart. The unsolved issues caused bitter inter-ethnic wars, with Croatia and Bosnia and Herzegovina being primarily affected by the conflicts.
The breakup of Yugoslavia was caused by a variety of factors, with the most important being the rise of ethnic nationalism. Following longtime Yugoslav leader Josip Broz Tito's death in 1980, Yugoslavia's weakened federal government faced rising economic and political challenges. In 1981, Albanians in Kosovo began to agitate for autonomy, leading to an upsurge in Serb nationalism. On 20 April 1987, President of SR Serbia Ivan Stambolic sent League of Communists of Serbia president Slobodan Milosevic to speak with Albanian communist officials in Kosovo about the rising nationalism in the poor region. However, on 24 April, Milosevic chose instead to meet with the Serbian nationalists, and he swore to defend them from the Albanians, who were falsely accused of burning down monasteries and forcing Serbs from their homes. Through a series of populist moves, he also acquired power in Vojvodina and Montenegro, garnering a high level of support for a centralized government from the Serb majority of Yugoslavia. The party leaders of Slovenia and Croatia opposed his centralization policies, which also advocated for greater democratization in response to the Revolutions of 1989.
In January 1990, the 14th Congress of the League of Communists of Yugoslavia was held in Belgrade, with Milosevic's centralization policies being the main issue. The Slovenian delegation, led by Milan Kucan, advocated for greater autonomy for the republics, but the Serbs rejected all of their demands. In response, Slovene delegation member Ciril Ribicic announced that the Slovenes were leaving the Communist Party, and the Slovene delegates walked out of the Congress. When Milosevic attempted to re-convene the congress without the Slovenes, the Croatian delegation followed the Slovenes in leaving, and the delegations of Vojvodina, Bosnia and Herzegovina, and Montenegro would also leave the congress. That same month, the communist associations in each republic began to change their names to "Socialist" or "Social Democratic" parties and abandon their communist inclinations. The League of Communists of Yugoslavia dissolved along federal lines, and republican communist organizations became separate socialist parties.
In 1990, the first free multi-party elections were held in Yugoslavia. The socialists (ex-communists) lost power to ethnic separatist parties in every state except for in Serbia and Montenegro, where Milosevic and his allies remained in power. Nationalist rhetoric on all sides became increasingly heated, with a deep rivalry developing between the Serbs and Croats for Croat president Franjo Tudman's reuse of the checkerboard cross that had previously been used as the flag of the fascist Independent State of Croatia, as well as due to the rebellion of the Serb policemen in Knin. Slovenia, Yugoslavia's wealthiest province, also sought to separate from the Belgrade-dominated Yugoslav government.
On 25 June 1991, Croatia and Slovenia declared independence from Yugoslavia, and Yugoslavia fought a ten-day war with Slovenia before making peace, with Slovenia agreeing to take part in further negotiations about the future of Yugoslavia. This freed up Yugoslav troops to put down Croatian independence, but Croatia proved to be a much different scenario. Croatia would fight with Yugoslavia for four years, and ethnic cleansing would become a major issue.
On 25 September 1991, Macedonia declared independence from Yugoslavia, and it became the only former Yugoslav republic to be formed without resistance from the Yugoslav government.
Bosnia and Herzegovina would prove to be perhaps the most complex problem resulting from the breakup of Yugoslavia. A multi-ethnic country with large pockets of Catholic Croats, Muslim Bosniaks, and Orthodox Serbs scattered across its territory, Bosnia was ethnically fragmented. In 1991, the nationalist leader Radovan Karadzic formed the Serb Democratic Party, and he warned the Bosniaks that any declaration of independence would send the country to Hell and the Muslims to extinction. On 3 March 1992, Bosnia and Herzegovina declared its independence, leading to the bloody Bosnian War, which was marked by ethnic cleansing and sheer brutality.
The wars left long-term economic and political damage in the region, with ethnic groups being displaced and nationlaism becoming a major threat to regional stability. In 1999, the Kosovo War would break out as the Kosovar Albanians rose up against the Yugoslav government, continuing the breakup and its after-effects.