Gacko () is a town and municipality in Republika Srpska, Bosnia and Herzegovina. It is situated in the region of East Herzegovina. As of 2013, the town has a population of 5,784 inhabitants, while the municipality has 8,990 inhabitants.
The municipality covers an area of , making it one of the largest municipalities in Bosnia and Herzegovina.
The town is near the state border with Montenegro.
In the 14th century the region was governed by the powerful VojinoviÃÂ family.
In 1359, veliki ÃÂelnik Dimitrije controlled the region.
The rebels were defeated at the field of Gacko. This was ultimately due to the lack of foreign support.
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 Ustaà ¡e 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 Perià ¡iàstarted 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.
Aside from the town of Gacko, the municipality includes the following settlements:
The Gacko coal mine and thermoelectric powerplant is located in the municipality, and is also the largest employer in the area.
The following table gives a preview of the total number of registered people employed in professional fields per their core activity (as of 2018):
The local football club, FK Mladost Gacko, plays in the First League of the Republika Srpska.
Volleyball teams, both men's and women's, are among the most successful in Bosnia and Herzegovina, with the women's volleyball team being vice champions multiple times, also winning the Cup of Republika Srpska once.