 The promised crusade, the fruit of John VIII's labor, ended only in disaster as it was defeated by the Turks at the Battle of Varna in 1444.In 1798, the Greek Orthodox Patriarch of Jerusalem, Anthemus, wrote that the Ottoman Empire had been imposed by God himself as the supreme empire on Earth due to the heretical dealings of the Palaiologan emperors with Christians in the West.There is no evidence that the final emperor, Constantine XI, ever repudiated the union achieved at Florence in 1439.