Wallachia continued its stance against the Ottomans, having stopped another expedition in the next year, 1397, and in 1400 yet another expedition of the Ottomans. The defeat and imprisonment of Sultan Bayezid I by Timur (Tamerlane) at Ankara in the summer of 1402 opened a period of anarchy in the Ottoman Empire and Mircea cel Batran took advantage of it to organize together with the Kingdom of Hungary a campaign against the Turks. The Hungarians, Poles and Walachians were defeated at the Battle of Varna in 1444, and Constantinople finally fell in 1453 to the Turks, followed by the Despotate of Morea in 1460, the Empire of Trebizond in 1461, and the Principality of Theodoro in 1475, which brought an end to the last vestiges of the Eastern Roman Empire, as well as the final remaining pockets of Greek resistance against the Ottoman Turks in both the Balkans and Anatolia.