In early February 1917, a rebellion led by Vojinović broke out in the vicinity of Kuršumlija and Prokuplje. The insurgents, supported by volunteers and Chetniks from Montenegro, liberated Kuršumlija, Prokuplje, Pusta Reka, Lebane and Ribarska. The uprising was planned to coincide with an Allied offensive. Later that month, a large scale uprising broke out in the Toplica District in Bulgarian-occupied Serbia. A force of 4,000 armed men and women managed to liberate a significant area in the Morava Valley before the uprising was put down. During the summer of 1917, the Austro-Hungarian Army was forced to bring in troops from the Isonzo Front to reinforce the Bulgarian Army and Bulgarian paramilitary groups. Without the expected Allied support, the uprising collapsed. In late 1917, Vojinović was killed; Pećanac managed to escape and went into hiding. According to contemporary Austro-Hungarian Army reports, 20,000 Serbs were killed in the course of the rebellion, while 2,600 managed to escape into the forests. Despite the harsh repression, guerrilla groups managed to survive and were able to support Allied offensive operations in the summer of 1918. After the war, Chief of Staff Paul Kirch described the withdrawal of the German 11th Army: