Case Black, also known as the Fifth Enemy Offensive in Yugoslav historiography and often identified with its final phase, the Battle of the Sutjeska was a joint attack by the Axis taking place from 15 May to 16 June 1943, which aimed to destroy the main Yugoslav Partisan force, near the Sutjeska river in south-eastern Bosnia. The failure of the offensive marked a turning point for Yugoslavia during World War II. It was also the last major German-Italian joint operation against the partisans.

The Socialist Federal Republic of Yugoslavia (SFRY), commonly referred to as SFR Yugoslavia or Socialist Yugoslavia or simply as Yugoslavia, was a country in Central and Southeast Europe. It emerged in 1945, following World War II, and lasted until 1992, breaking up as a consequence of the Yugoslav Wars. Spanning an area of 255,804 square kilometres (98,766 sq mi) in the Balkans, Yugoslavia was bordered by the Adriatic Sea and Italy to the west, Austria and Hungary to the north, Bulgaria and Romania to the east, and Albania and Greece to the south. It was a one-party socialist state and federation governed by the League of Communists of Yugoslavia, and had six constituent republics: Bosnia and Herzegovina, Croatia, Macedonia, Montenegro, Serbia, and Slovenia. Within Serbia was the Yugoslav capital city of Belgrade as well as two autonomous Yugoslav provinces: Kosovo and Vojvodina.