Middle Ages In the 14th century the region was governed by the powerful
Vojinović family. In 1359,
veliki čelnik Dimitrije controlled the region.
Ottoman period The rebels were defeated at the
field of Gacko. This was ultimately due to the lack of foreign support.
Modern history Austro-Hungarian authorities took it over in 1878, a decision which was made at the
Berlin Congress. In 1908, Austria-Hungary annexed Bosnia and Herzegovina sparking the
Bosnian Crisis, which eventually led to
World War I. The Croatian fascist
Ustaše movement committed the
Gacko massacre on 4 June 1941. In response, on 6 June 1941 the rebels from Gacko under the command of Orthodox priest
Radojica Perišić started the uprising against the
Independent State of Croatia known as the
June 1941 uprising in eastern Herzegovina. The first Partisan battalion established in Gacko at the end of 1941 was named "6th June" in honor of the first date of the uprising. During the period after the
Fall of the Berlin Wall, the Gacko municipality proclaimed 6 June as their holiday in honor of the beginning of the uprising and held public ceremonies on 6 June named the
Day of Gacko. When the German and Italian
Zones of Influence were revised on 24 June 1942, Gacko fell in , administered civilly by Croatia but militarily by Italy. ==Settlements==