[shentov]

The April Uprising (Bulgarian: Априлско въстание) was an insurrection organised by the Bulgarians in the Ottoman Empire from April to May 1876, the indirect result of which was the liberation of Bulgaria in 1878.
The uprising broke out as a result of the severe internal and external problems which the Ottoman Empire experienced in the middle of the 1870s. In 1875, taxes levied on non-Muslims were raised for fear of a state bankrupt, which, in its turn, caused tension between Muslims and Christians and triggered an insurrection in Bosnia and Herzegovina. The failure of the Ottomans to handle the uprising successfully showed the weakness of the Ottoman state while the brutalities which ensued, discredited additionally the empire to the outside world.

http://en.wikipedia.org/wiki/April_uprising