Frederick II launched a crusade in 1228. although he did not fight one battle, he secured great concessions from Turks. Jerusalem, except for the Mosque of Omar, was surrendered to him, as well as several cites and strongholds. All Christian slaves were released. Frederick promised to protect the sultan against his enemies. Frederick entered Jerusalem and crowned himself King of Jerusalem. Nazareth, Bethlehem, and several other holy places were recovered at the same time. The Turks recaptured Jerusalem in 1244.