Task: Question Answering
Input (English): Passage: The Ottomans were employed as mercenaries by the Byzantines in the 1340s but later became invaders in their own right. Sultan Murad I took Adrianople from the Byzantines in 1362; Sofia fell in 1382, followed by Shumen in 1388. The Ottomans completed their conquest of Bulgarian lands in 1393 when Tarnovo was sacked after a three-month siege and the Battle of Nicopolis which brought about the fall of the Vidin Tsardom in 1396. Sozopol was the last Bulgarian settlement to fall, in 1453. The Bulgarian nobility was subsequently eliminated and the peasantry was enserfed to Ottoman masters, while much of the educated clergy fled to other countries.Christians were considered an inferior class of people under the Ottoman system. Bulgarians were subjected to heavy taxes (including devshirme, or blood tax), their culture was suppressed, and they experienced partial Islamisation. Ottoman authorities established a religious administrative community called the Rum Millet, which governed all Orthodox Christians regardless of their ethnicity. Most of the local population then gradually lost its distinct national consciousness, identifying only by its faith. The clergy remaining in some isolated monasteries kept their ethnic identity alive, enabling its survival in remote rural areas, and in the militant Catholic community in the northwest of the country.As Ottoman power began to wane, Habsburg Austria and Russia saw Bulgarian Christians as potential allies. The Austrians first backed an uprising in Tarnovo in 1598, then a second one in 1686, the Chiprovtsi Uprising in 1688 and finally Karposh's Rebellion in 1689. The Russian Empire also asserted itself as a protector of Christians in Ottoman lands with the Treaty of Küçük Kaynarca in 1774.
The Western European Enlightenment in the 18th century influenced the initiation of a national awakening of Bulgaria. It restored national consciousness and provided an ideological basis for 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 military solution without risking confrontation with other Great Powers, as had happened in the Crimean War. In 1877 Russia declared war on the Ottomans and defeated them with the help of Bulgarian rebels, particularly during the crucial Battle of Shipka Pass which secured Russian control over the main road to Constantinople. 
Question: What was the name of the rebellion the Ottoman's put down in 1876?
Output (English): April Uprising.