Since November 1915, when Serbia was occupied, the Bulgarian army launched crimes against the civilian population. The use of the Serbian language was banned and books in the Serbian language were burned in Niš and Leskovac. Then Bulgarian soldiers started public executions against those that declared themselves Serbian, the worst was in Surdulica, where an estimated 2,000–3,000 Serbian men were executed in two years. The Serbs could no longer tolerate the violence of the Bulgarians and in 1917 raised the Toplica Uprising. However, the Bulgarians quickly suppressed the uprising. To "punish" Serbs, they killed over 20,000 civilians and guerrillas. To this day, Bulgarians blame the Austro-Hungarians for mass executions, although there are reliable sources that confirm their culpability. Fortunately, Bulgaria's crimes came to an end with the Allied breakthrough of the Macedonian Front. Then Serbs, British and French liberated Serbian cities under Bulgarian occupation. The Serbs wanted to launch an offensive against Bulgaria, but the British did not allow them, fearing that the Serbs could take revenge on the Bulgarians for their war crimes.