In 1137 while the Christians and Muslims were engaged with each other a new force was entering the area. John, the Byzantine Emperor was moving against Antioch. He decided to take back the city and began attacking the walls. Too powerful for Fulk to deal with he decided to surrender Antioch to the Emperor. The Prince of Antioch, Raymond of Poitiers, had to surrender to the Emperor in person. Then, with the Byzantine flag above the city and Raymond still the Prince, the Emperor returned to Constantinople. Fulk, the King of Jerusalem, lost his control over Antioch.