John, or Ioannis (Ἰωάννης), Palaiologos (Παλαιολόγος) was a Byzantine and Eastern Roman emperor of the 14th century. His three reigns were marked by the dissolution of territory to the Ottoman Turks and civil war. The civil wars were between Ioannis VI Kantakouzenos and Matthaios Kantakouzenos. In desperation, John V even appealed to Pope Urban V for a reunion with Rome in exchange for an attack against the Ottomans and converted to Catholicism.