The Byzantine-Ottoman Wars were a series of decisive conflicts between the Ottoman Turks and the Byzantine Greeks that led to the final destruction of the Byzantine Empire and the rise of the Ottoman Empire. After the loss of Constantinople in 1204 the Byzantine Empire was left divided and in chaos; taking advantage of the situation the Sultanate of Rum began seizing territory in Western Asia Minor until the Nicaean Empire was able to repulse the Seljuk Turks against the remaining territories still under Greek rule. Eventually Constantinople was re-taken from the hated Latin Empire in 1261 by the Nicaean Empire. However the position of the Byzantine Empire in the European continent remained uncertain due to the presence of the rival kingdoms of the Despotate of Epirus, Serbia and the Second Bulgarian Empire. This, combined with the reduced power of the Sultanate of Rum (Byzantium's chief rival in Asia) led to the removal of troops from Asia Minor to maintain Byzantium's grip on Thrace. However the weakening of the Sultanate of Rum was by no means a blessing to the Empire as fanatical ghazis began setting up their fiefdoms, at the expense of the Byzantine Empire. Whilst many Turkic Beys participated in the conquest of Byzantine and Seljuk territory, the territories under the control of the Bey Osman I poses the greatest threat to Nicaea and to Constantinople. By 1299, Osman I felt assured of his position to declare himself Sultan and there after his territories became known as the Ottoman Empire. Within 50 years of Osman I's establishment of the Ottoman beylik, Byzantine Asia Minor had ceased to exist and by ca. 1380, Byzantine Thrace was lost to the Ottomans. By ca. 1400, the once mighty Byzantine Empire was nothing more than a collection of the Despotate of Morea, a few Aegean islands and a strip of land in Thrace in the immediate vicinity of the Capital. The Crusade of Nicopolis in 1396, Timur's invasion in 1402 and the final Crusade of Varna in 1444 allowed a ruined Constantinople to stave off defeat until 1453. With the conclusion of the war Ottoman supremacy became established in the eastern Mediterranean.