Bosnia and Herzegovina, republic in south-eastern Europe, in the Balkan Peninsula, bounded on the north and west by Croatia, and on the east and south by Serbia and Montenegro. Formerly a constituent republic of the Socialist Federal Republic of Yugoslavia, Bosnia and Herzegovina declared its freedom in March 1992. Civil war then broke out in the nation as Bosnia and Herzegovina became involved in the Bosnian-Croatian-Serbian War. Bosnia and Herzegovina has a territory of about 51,130 sq km. Sarajevo is the republic's capital and largest city.