 Several Bulgarian revolts erupted throughout the nearly five centuries of Ottoman rule , most notably the Habsburg @-@ backed Tarnovo uprisings in 1598 and in 1686 , the Chiprovtsi Uprising in 1688 and <unk> 's Rebellion in 1689 . In the 18th century , the Enlightenment in Western Europe provided influence for the initiation of a movement known as the National awakening of Bulgaria . It restored national consciousness and became a key factor in the liberation struggle , resulting in the 1876 April Uprising . Up to 30 @,@ 000 Bulgarians were killed as Ottoman authorities put down the rebellion . The massacres prompted the Great Powers to take action . They convened the Constantinople Conference in 1876 , but their decisions were rejected by the Ottomans . This allowed the Russian Empire to seek a solution by force without risking military confrontation with other Great Powers , as had happened in the Crimean War . In 1877 Russia declared war on the Ottoman Empire and defeated its forces with the help of Bulgarian volunteers . 
