The region covered by Bosnia-Herzegovina was part of the Roman Empire. By the 13th century the region accepted Hungarian kings as overlords. In the 14th century Bosnia became a kingdom and ruled Herzegovina. Both fell in the 15th century to the Turks, who combined them. In 1878 Austria-Hungary occupied Bosnia-Herzegovina, and in 1908 annexed it. In 1918 it was incorporated into what became Yugoslavia.

Bosnia-Herzegovina remained a part of Yugoslavia until 1992, when it seceded. Serbian nationalists in Bosnia-Herzegovina opposed secession, and war broke out between them and the country's Croats and Slavic Muslims.

The war raged throughout 1992 and by the end of that year Serbian nationalist, who were backed by the Serb-led federal Yugoslav army, had occupied nearly 70 per cent of the country. Nationalist Bosnian Croats also began seizing territory. All sides in the war engaged in a policy of murdering or expelling from their territory (or territories they conquered) people who were not of their ethnic group. The United Nations condemned such actions as war crimes. Also in 1992, the United Nations sent forces to the country to protect civilians and distribute relief supplies.

Fighting continued during 1993, despite various UN attempts to establish peace. In early 1994 forces of the North Atlantic Treaty Organization (NATO), acting under UN authorization, launched air strikes against Serb forces to protect civilians and UN forces from attack. Serb sieges of some cities were lifted but the war continued. Later that year Bosnian Croats and Slavic Muslims ceased hostilities against each other and formed a federation. The Bosnian Serbs, however, continued to fight.

In July and August, 1995, several socalled safe areas (regions under the protection of UN forces) were attacked by Bosnian Serb forces and some were captured. Shortly afterward NATO launched an intense campaign of air strikes against Bosnian Serb military sites. In a major offensive in September, Bosnian government troops recaptured a large section of Serbheld territory. Shortly afterward, partly as a result of United States diplomatic efforts, a cease-fire was signed.

In November, 1995, a peace accord was signed in Dayton, Ohio, ending the conflict that had cost some 200,000 lives. The peace treaty called for a unitary Bosnian state made up of two largely autonomous states (one Serb, the other Muslim and Croat). The treaty also called for national elections and the deployment of a NATO peacekeeping force, which included troops from the United States. National elections were held in September, 1996.

The European Union (EU) took control of peacekeeping operations in 2004.