The Second Kingdom of Jerusalem reached its pinnacle in the year 1243. Not only were the last vestiges of Hohenstaufen rule expelled from Outremer in that year, but also the Franks reoccupied Jerusalem including the Temple Mount by the Franks. Yet this very success was like a Trojan Horse; the seeds of the kingdom's destruction were hidden in the apparent victory. This did not, however, immediately become apparent.
The reoccupation of Jerusalem had been made possible by a new alliance with as-Salih Ismail (now the ruler of Damascus) and his cousin an-Nasir Daud, who controlled Transjordan. These princes offered the Franks additional and substantial territorial concessions in exchange for an offensive alliance directed at their hated rival (and relative) in Cairo: as-Salih Ayyub. This treaty differed significantly from earlier treaties, particularly the truce with Frederick II in that it recognised Christianity’s higher claim to Jerusalem and the right of the Christians to build fortifications. Furthermore, it gave the Franks the territory around Jerusalem necessary for its defence and viability. In short, it laid the foundation for what could have been a more sustainable Frankish state.
The Egyptians allied themselves with the Kharasmians, a Turkish tribe displaced by the Mongol invasions of 1220. Whether this alliance provoked the Damascene approach to the Franks or was itself a response to the Frankish/Damascene alliance is unclear. In any case, in 1244, the Kharasmians swept into Syria and rapidly took control of the regions of the kingdom recently restored to Frankish rule. In August, they took Jerusalem and engaged in an orgy of destruction that left churches desecrated, the Holy Sepulchre gutted, and at least 5,000 mostly native Christians dead.
The Franks and their Ayyubid allies mustered their armies and prepared for the showdown with Egypt. The Frankish army probably equaled it in size that which had been fielded at Hattin in 1187 with as many as 1,200 knights, but with one striking difference: as many as 1,100 of those knights were members of the military orders rather than civilian knights. Also striking is that the muster took place in Acre, where the Saracen leaders were welcomed and hosted by the Knights Templar. The combined Frankish/Saracen army advanced via Jaffa and Ascalon to Gaza on the border of the kingdom. On 17 October 1244, this army confronted the Egyptian Ayyubid forces and their Kharasmian allies. In a battle lasting two days, the Egyptians and Kharasmians won the upper hand. They shattered the Damascene/Transjordan wing first, setting it to flight, and then ground down the Franks.
Muslim casualties amounted to 25,000 men, while the Franks lost 16,000. These casualties included the Master of the Teutonic Knights along with nearly all 400 Teutonic Knights, 312 Templars, 325 Hospitallers and all fighting members of the Knights of St. Lazarus. Both the Templar and Hospitaller Masters were taken prisoner along with thirty-four other Templars, twenty-six Hospitallers and three Teutonic Knights. Also among the prisoners was the Lord of Jaffa, Walter de Brienne, who was tortured in front of Jaffa to persuade the city to surrender. The garrison steadfastly refused to submit, and Brienne died of his injuries in captivity months later.
The sultan of Cairo followed up his victory by conquering his Muslim opponents’ territories in Transjordan and Syria, thereby re-establishing the dominance of the sultan of Cairo over the Ayyubid empire. Yet he made no attempt to subdue the Kingdom of Jerusalem. While this sounds astonishing, there were good reasons for restraint. First and foremost, As-Salih Ayyub was not engaged in ‘jihad’. He had fought the Franks not because of their religion but because they were allied with his Muslim enemies. His self-interest in continued trade with and through the crusader states remained intact.
Furthermore, he knew that while the losses of the military orders at La Forbie were huge, the secular chivalry had suffered hardly at all. The great lords of Beirut, Sidon, Toron, Caesarea and Arsuf do not appear to have been engaged in the battle. Their fighting capacity remained undiminished, as did the entire feudal host of Cyprus, a significant point since, at this time, King Henry of Cyprus was recognised as the regent of Jerusalem by the local barons. Clearly, in an all-out assault on the heart of the crusader kingdom, the Franks would have been able to put up a tenacious defence. The sultan of Cairo wisely sought to avoid such a confrontation possibly because he was also facing an increasingly dangerous threat from the Mongols in the north.
Finally, the Ayyubid fear of a new crusade sat deep — and not unjustified. In December 1244, a dying young man vowed that if God would grant him a reprieve, he would recapture Jerusalem for Christendom. He experienced a miraculous recovery and was to prove one of the most determined and tenacious of all crusaders: King Louis IX of France.
The bulk of this entry is an excerpt from Dr. Schrader's comprehensive study of the crusader states.