The Ninth Crusade, which is sometimes grouped with the Eighth Crusade, is commonly considered to be the last major medieval Crusade to the Holy Land. It took place in 1271–1272.
Louis IX of France's failure to capture Tunis in the Eighth Crusade led Prince Edward of England to sail to Acre in what is known as the Ninth Crusade. The Ninth Crusade failed largely because the Crusading spirit was nearly "extinct," and because of the growing power of Baibars and the Mamluks in Egypt. It also foreshadowed the imminent collapse of the last remaining crusader strongholds along the Mediterranean coast.

Prologue

Following the Mamluk victory over the Mongols in 1260 at the Battle of Ain Jalut by Qutuz and his general Baibars, Qutuz was assassinated, leaving Baibars to claim the sultanate for himself. As Sultan, Baibars proceeded to attack the Christian crusaders at Arsuf, Athlith, Haifa, Safad, Jaffa, Ascalon, and Caesarea. As the Crusader fortress cities fell one by one, the Christians sought help from Europe, but assistance was slow in coming.

In 1268 Baibars captured Antioch, thereby destroying the last remnant of the Principality of Antioch, securing the Mamluk northern front and threatening the small Crusader County of Tripoli.
Louis IX of France, having already organized a large crusader army with the intent of attacking Egypt, was diverted instead to Tunis, where Louis himself died in 1270. Prince Edward of England arrived in Tunis too late to contribute to the remainder of the crusade in Tunis. Instead, he continued on his way to the Holy Land to assist Bohemund VI, Prince of Antioch and Count of Tripoli, against the Mamluk threat to Tripoli and the remnant of the Kingdom of Jerusalem.

Crusader operations in the Holy Land

It was decided that Edward along with Louis' brother Charles of Anjou would take their forces onward to Acre, capital of the remnant of the Kingdom of Jerusalem and the final objective of Baibars' campaign. The army of Edward and Charles arrived in 1271, just as Baibars was besieging Tripoli, which as the last remaining territory of the County of Tripoli was full of tens of thousands of Christian refugees. From their bases in Cyprus and Acre, Edward and Charles managed to attack Baibars' interior lines and break the siege.

As soon as Edward arrived in Acre, he made some attempts to form a Franco-Mongol alliance, sending an embassy to the Mongol ruler of Persia Abagha, an enemy of the Muslims. The embassy was led by Reginald Rossel, Godefroi of Waus and John of Parker, and its mission was to obtain military support from the Mongols. In an answer dated September 4, 1271, Abagha agreed for cooperation and asked at what date the concerted attack on the Mamluks should take place.

The arrival of the additional forces of Hugh III of Cyprus further emboldened Edward, who engaged in a raid on the town of Qaqun. At the end of October 1271, a small force of Mongols arrived in Syria and ravaged the land from Aleppo southward. However Abagha, occupied by other conflicts in Turkestan could only send 10,000 Mongol horsemen under general Samagar from the occupation army in Seljuk Anatolia, plus auxiliary Seljukid troops. Despite the relatively small force though, their arrival still triggered an exodus of Muslim populations (who remembered the previous campaigns of Kithuqa) as far south as Cairo.

But the Mongols did not stay, and when the Mamluk leader Baibars mounted a counter-offensive from Egypt on November 12th, the Mongols had already retreated beyond the Euphrates.

In the interim, Baibars came to suspect there would be a combined land-sea attack on Egypt. Feeling his position sufficiently threatened, he endeavored to head off such a maneuver by building a fleet. Having finished construction of the fleet, rather than attack the Crusader army directly, Baibars attempted to land on Cyprus in 1271, hoping to draw Hugh III of Cyprus (the nominal King of Jerusalem) and his fleet out of Acre, with the objective of conquering the island and leaving Edward and the crusader army isolated in the Holy Land. However, in the ensuing naval campaign the fleet was destroyed and Baibars' armies were forced back.

Following this victory, Edward realized that to ensure long-term resistance it was necessary to end the internal unrest within the Christian state, and so he mediated between Hugh and his unenthusiastic knights from the Ibelin family of Cyprus. After the mediation, Prince Edward of England began negotiating an eleven-year truce with Baibars, although this negotiation almost ended when Baibars attempted to assassinate him by sending men pretending to seek baptism as Christians. Edward and his knights personally killed the assassins and at once began preparations for a direct attack on Jerusalem. However, when news arrived that Edward's father Henry III had died, a treaty was signed with Baibars, allowing Edward to return home to be crowned King of England in 1272.

Aftermath

Edward had been accompanied by Theobald Visconti, who became Pope Gregory X in 1271. Gregory called for a new crusade at the Council of Lyons in 1274, but nothing came of this. Meanwhile new fissures arose within the Christian states when Charles of Anjou took advantage of a dispute between Hugh III, the Knights Templar, and the Venetians in order to bring the remaining Christian state under his control. Having bought Mary of Antioch's claims to the Kingdom of Jerusalem, he attacked Hugh III, causing a civil war within the rump kingdom. In 1277 Roger of San Severino captured Acre for Charles.

Although the internecine war within the crusaders' ranks had proven debilitating, it provided the opportunity for a single commander to take control of the crusade in the person of Charles. However, this hope was dashed when Venice suggested a crusade be called not against the Mamluks but against Constantinople, where Michael VIII had recently re-established the Byzantine Empire and driven out the Venetians. Pope Gregory would not have supported such an attack, but in 1281 Pope Martin IV assented to it; the ensuing fiasco helped lead to the Sicilian Vespers on March 31, 1282, instigated by Michael VIII, and Charles was forced to return home. This was the last expedition launched against the Byzantines in Europe or the Muslims in the Holy Land.

The remaining nine years saw an increase in demands from the Mamluks, including tribute, as well as increased persecution of pilgrims, all in contravention of the truce. In 1289, Sultan Qalawun gathered a large army and invested the remnants of the county of Tripoli, ultimately laying siege to the capital and taking it after a bloody assault. The attack on Tripoli however was particularly devastating to the Mamluks as the Christian resistance reached fanatical proportions and Qalawun lost his eldest and most able son in the campaign. He waited another two years to regather his strength.

In 1291, a group of pilgrims from Acre came under attack and in retaliation killed nineteen Muslim merchants in a Syrian caravan. Qalawun demanded they pay an extraordinary amount in compensation. When no reply came, the Sultan used it as a pretext to besiege Acre, and finish off the last independent Crusader state occupying the Holy Land. Qalawun died during the siege, leaving Khalil, the sole surviving member of his family, as Mamluk Sultan. With Acre seized, the Crusader States ceased to exist. The center of power of the Crusaders was moved northwards to Tortosa, and eventually offshore to Cyprus. The last remaining foothold on the Holy Land, Ruad Island, was lost in 1302/1303. The period of the Crusades to the Holy Land was over, almost two hundred years after Pope Urban II had called for the first of these holy wars.