Crusade successfully returned Jerusalem to Christian rule and had set a precedent, in having achieved success on crusade without papal involvement. The Crusades of 1239–1241 The Crusades of 1239–1241, also known as the Barons' Crusade, were a series of crusades to the Holy Land that, in territorial terms, were the most successful since the First Crusade. The major expeditions were led separately by Theobald I of Navarre and Richard of Cornwall. These crusades are sometimes discussed along with that of Baldwin of Courtenay to Constantinople. In 1229, Frederick II and the Ayyubid sultan al-Kamil, had agreed to a ten-year truce. Nevertheless, Gregory IX, who had condemned this truce from the beginning, issued the papal bull Rachel suum videns in 1234 calling for a new crusade once the truce expired. A number of English and French nobles took the cross, but the crusade's departure was delayed because Frederick, whose lands the crusaders had planned to cross, opposed any crusading activity before the expiration of this truce. Frederick was again excommunicated in 1239, causing most crusaders to avoid his territories on their way to the Holy Land. The French expedition was led by Theobald I of Navarre and Hugh of Burgundy, joined by Amaury of Montfort and Peter of Dreux. On 1 September 1239, Theobald arrived in Acre, and was soon drawn into the Ayyubid civil war, which had been raging since the death of al-Kamil in 1238. At the end of September, al-Kamil's brother as-Salih Ismail seized Damascus from his nephew, as-Salih Ayyub, and recognized al-Adil II as sultan of Egypt. Theobald decided to fortify Ascalon to protect the southern border of the kingdom and to move against Damascus later. While the Crusaders were marching from Acre to Jaffa, Egyptian troops moved to secure the border in what became the Battle at Gaza. Contrary to Theobald's instructions and the advice of the military orders, a group decided to move against the enemy without further delay, but they were surprised by the Muslims who inflicted a devasting defeat on the Franks. The masters of the military orders then convinced Theobald to retreat to Acre rather than pursue the Egyptians and their Frankish prisoners. A month after the battle at Gaza, an-Nasir Dā'ūd, emir of Kerak, seized Jerusalem, virtually unguarded. The internal strife among the Ayyubids allowed Theobald to negotiate the return of Jerusalem. In September 1240, Theobald departed for Europe, while Hugh