Invasions and Conquests in the Late Middle Ages
The Southeastern Europe and Byzantine Empire were faced with the Ottoman invasions at the same time when the Western Europe witnessed the rise of centralized nation-states and entered the Age of Discovery or Age of Exploration. The Byzantine Empire greatly weakened after the Fall of Constantinople during the Fourth Crusade in 1204 was slowly falling into the Ottoman hands. The Ottomans captured Gallipoli in 1354 and Byzantine Emperor was forced to pay tribute to the Ottoman Sultan from 1399 onwards. The Ottoman forces invaded Southeastern Europe in the middle of the 14th century and defeated the coalition of Serb lords in the Battle of Kosovo in 1389. Despite a major victory the Ottoman army withdrew but few decades later Serbia became an Ottoman vassal state.
When Bulgaria was made an Ottoman vassal state in 1393 the Turks had an open way to Hungary which failed to organize a crusade against the Ottomans. The Ottoman territorial expansion and conquests in Europe were halted by the invasion of the Mongols under Timur but after Timur’s death in 1405 the Ottoman expansion continued. Mehmed II the Conqueror (1451-81) captured Constantinople (1453) and conquered Morea (1460), Serbia (1459), Bosnia (1463) and Albania (1467), while Wallachia and the Crimean Khanate were forced to pay tribute to the Ottoman Empire. The Fall of Constantinople in 1453 attracted attention of all Europe. Combined Western European forces defeated the Ottomans at Belgrade in 1456 and halted the Ottoman advance towards Catholic Europe for seven decades. However, all attempts to destroy the Ottoman Empire failed.