In addition, the front line between Islam and Christianity had been moving slowly towards the Kingdom of Hungary. In the eyes of the Bulgarian boyars, despots, and other independent Balkan rulers, the crusade was a great chance to reverse the course of the Ottoman conquest and take back the Balkans from Islamic rule. In 1393 the Bulgarian tsar Ivan Shishman had lost Nicopolis - his temporary capital - to the Ottomans, while his brother, Ivan Stratsimir, still held Vidin but had been reduced to an Ottoman vassal.
After the Battle of Kosovo in 1389, the Ottomans had conquered most of the Balkans and had reduced the Byzantine Empire to the area immediately surrounding Constantinople, which they blockaded from 1394 on. Most recently there had been a failed crusade against Tunisia in 1390, and there was ongoing warfare in northern Europe along the Baltic coast. There were many minor crusades in the 14th century, undertaken by individual kings or knights.
Crusades against heretics and schismatics
