However, most relations with the Mamluks were not as cordial. With the rise of the Mamluk Sultanate in Egypt in 1250, the destruction of the remaining Crusader territories gathered pace. After the Battle of Ain Jalut, Mamluk forces began attacking Crusader holdings as early as 1261 under Sultan Baibars. In 1265, Caesarea, Haifa, and Arsuf all fell to the Sultan. The following year saw the loss of all the important Latin holdings in Galilee. In 1268 Antioch was taken.
To help redress these losses, a number of minor Crusading expeditions left Europe for the East. The abortive Crusade of Louis IX of France to Tunis in 1270 was one such attempt. The minor Ninth Crusade of Prince Edward (later King Edward I) of England in 1271-1272 was another. Neither of these expeditions was capable of giving any sound assistance to the beleaguered Latin states. The forces involved were too small, the duration of each of the Crusades too short, the interests of the participants too diverse to allow any solid accomplishment.
Pope Gregory X labored valiantly to excite some general enthusiasm for another great Crusade, but he labored in vain. The failure of his appeal was variously ascribed by the Pope's advisors to the laziness and vice of the European nobility and to clerical corruption. Though each of these factors may have been in part to blame, a more basic reason for the failure seems to have been the debasement of the ideal of the Crusade itself. The use by Gregory X's predecessors of the label and privileges of the Crusade to recruit armies which could fight the Papacy's European enemies had done much to throw the whole movement into disrepute.
In any event, no Crusade of any major importance was forthcoming, despite the Pope's best efforts. Meanwhile the attacks on the Latin East continued, as did also the internal difficulties within what was left of the Latin Kingdom. By 1276, the situation, both external and internal, had become so perilous that the "King of Jerusalem" Henry II withdrew from Palestine altogether to take up his abode on the Island of Cyprus. The desperate plight of the Latin Kingdom worsened. In 1278, Lattakia fell. In 1289 Tripoli was lost in the Fall of Tripoli.
Only a small army of peasant and unemployed townfolks from Tuscany and Lombardy could be raised. They were transported in 20 Venetian galleys. They were led by Nicholas Tiepolo, the son of the Doge, who was assisted by the returning Jean de Grailly and Roux of Sully. As they sailed eastward, the fleet was joined by five galleys from king James of Aragon who wished to help despite his conflict with the Pope and Venice.
However, the inexperienced and poorly controlled lot of peasants from Italy were the authors of a massacre against Muslim merchants and peasants in and around Acre in August of 1290. These killings gave the Mamluk Sultan Qalawun a pretext to attack the city. Qalawun asked for the men guilty of the massacre to be remitted to him so that he could apply justice. After discussions of possibly remitting the Christian criminals from Acre's jails, an idea of Guillaume de Beaujeu, the Council of Acre finally refused to remit anybody to Qalawun, and instead tried to argue that the killed Muslims had died because of their own fault.
Although a ten-year truce had been signed in 1289, Qalawun deemed the truce void following the killings. By October, Qalawun had ordered a general mobilization. Though the Sultan died in November, he was succeeded by his son Khalil, who would lead the forces attacking Acre.
The population of Acre at the time was estimated to be 40,000, with troops numbering around 15,000, and an additional 2,000 troops coming on May 6 with Henry II from Cyprus. There are no reliable figures for the Mamluk army, though estimates place it at 20,000 to 30,000 with most of the force being volunteer siege workers.
The siege itself lasted only six weeks, beginning on April 6 and ending with the fall of the city on May 18, though the Templars would hold out in their fortified headquarters until the 28th.
Within months, the remaining Crusader-held cities fell easily, including Sidon (July 14), Haifa (July 30), Beirut (July 31), Tartus (August 3), and Atlit (August 14). Only the small island of Arwad off the Syrian coast would hold out until 1302/1303.
The Latin Kingdom continued to exist, theoretically, on the island of Cyprus. There the Latin kings schemed and planned to recapture the mainland, but in vain. Money, men, and the will to do the task were all lacking. One last effort was made by King Peter I in 1365, when he successfully landed in Egypt and sacked Alexandria. Once the city was pillaged, however, the Crusaders returned as speedily as possible to Cyprus to divide their loot. As a crusade, the episode was utterly futile.
The fourteenth century saw some other crusades organized, but these enterprises differed in many ways from the eleventh and twelfth century expeditions which are properly called Crusades. The crusades of the fourteenth century aimed not at the recapture of Jerusalem and the Christian shrines of the Holy Land, but rather at checking the advance of the Ottoman Turks into Europe. While many of the crusaders in these fourteenth century undertakings looked upon the defeat of the Ottomans as a preliminary to the ultimate recapture of the Holy Land, none of the later crusades attempted any direct attack upon Palestine or Syria.