Toplica Uprising is the only national uprising against the occupying forces in the World War I, led by the Chetniks under the leadership of Kosta Vojinović and Kosta Pećanac. The rebellion started in 1917 against the Bulgarians who imposed terror on the Serbian population. The Serbian General Headquarters sent help, but the Bulgarians were faster and engaged large forces to break the uprising. Twenty thousand people were killed and 100.000 were taken prisoners to the Bulgarian camps. Despite that, the uprising was not suppressed.