<P> Late 13th - century politics in the Eastern Mediterranean were complex, with a number of powerful interested parties . Baibars had three key objectives: to prevent an alliance between the Latins and the Mongols, to cause dissension between the Mongols particularly between the Golden Horde and the Persian Ilkhanate, and to maintain access to a supply of slave recruits from the Russian steppes . In this he developed diplomatic ties with Manfred, King of Sicily, supporting him against the Papacy and Louis IX's brother Charles of Anjou . The Crusader states were fragmented, and various powers were competing for influence . In the War of Saint Sabas, Venice drove the Genoese from Acre to Tyre where they continued to trade happily with Baibars' Egypt . Indeed, Baibars negotiated free passage for the Genoese with Michael VIII Palaiologos, Emperor of Nicaea, the newly restored ruler of Constantinople . </P> <P> The French, led by Charles, similarly sought to expand their influence; Charles seized Sicily and Byzantine territory while marrying his daughters to the Latin claimants to Byzantium . To create his own claim to the throne of Jerusalem, Charles executed one rival and purchased the rights to the city from another . In 1270 Charles turned his brother King Louis IX's last Crusade, known as the Eighth Crusade, to his own advantage by persuading Louis to attack his rebel Arab vassals in Tunis . Louis' army was devastated by disease, and Louis himself died at Tunis on 25 August . Louis' fleet returned to France, leaving only Prince Edward, the future king of England, and a small retinue to continue what is known as the Ninth Crusade . Edward survived an assassination attempt organised by Baibars, negotiated a ten - year truce, and then returned to manage his affairs in England . This ended the last significant crusading effort in the Eastern Mediterranean . The 1281 election of a French pope, Martin IV, brought the full power of the papacy into line behind Charles . He prepared to launch a crusade against Constantinople but, in what became known as the Sicilian Vespers, an uprising fomented by Michael VIII Palaiologos deprived him of the resources of Sicily, and Peter III of Aragon was proclaimed king of Sicily . In response, Martin excommunicated Peter and called for an Aragonese Crusade, which was unsuccessful . In 1285 Charles died, having spent his life trying to amass a Mediterranean empire; he and Louis had viewed themselves as God's instruments to uphold the papacy . </P> <P> The causes of the decline in Crusading and the failure of the Crusader States is multi-faceted . Historians have attempted to explain this in terms of Muslim reunification and Jihadi enthusiasm but Thomas Asbridge, amongst others, considers this too simplistic . Muslim unity was sporadic and the desire for Jihad ephemeral . The nature of Crusades was unsuited to the conquest and defence of the Holy Land . Crusaders were on a personal pilgrimage and usually returned when it was completed . Although the philosophy of Crusading changed over time, the Crusades continued to provide short - lived armies without centralised leadership led by independently minded potentates . What the Crusader states needed were large standing armies . Religious fervour enabled amazing feats of military endeavour but proved difficult to direct and control . Succession disputes and dynastic rivalries in Europe, failed harvests and heretical outbreaks, all contributed to reducing Latin Europe's concerns for Jerusalem . Ultimately, even though the fighting was also at the edge of the Islamic world, the huge distances made the mounting of Crusades and the maintenance of communications insurmountably difficult . It enabled Islam, under the charismatic leadership of Nur al - Din and Saladin as well as the ruthless Baibars to use the logistical advantages from proximity to victorious effect . The mainland Crusader states of the outremer were finally extinguished with the fall of Tripoli in 1289 and Acre in 1291 . Many Latin Christians were evacuated to Cyprus by boat, were killed or enslaved . </P> <P> The success of the First Crusade inspired 12th - century popes such as Celestine III, Innocent III, Honorius III, and Gregory IX to call for military campaigns with the aim of Christianising the more remote regions of northern and north - eastern Europe . These campaigns are known as the Northern Crusades . The Wendish Crusade of 1147 saw Saxons, Danes, and Poles attempt to forcibly convert the tribes of Mecklenburg and Lusatia, who were Polabian Slavs or "Wends". Celestine III called for a Crusade in 1193, but when Bishop Berthold of Hanover responded in 1198, he led a large army into defeat and to his death . In response, Innocent III issued a bull declaring a Crusade, and Hartwig of Uthlede, Bishop of Bremen, along with the Brothers of the Sword brought all of the north - east Baltic under Catholic control . Konrad of Masovia gave Chelmno to the Teutonic Knights in 1226 as a base for a Crusade against the local Polish princes . The Livonian Brothers of the Sword were defeated by the Lithuanians, so in 1237 Gregory IX merged the remainder of the order into the Teutonic Order as the Livonian Order . By the middle of the century, the Teutonic Knights completed their conquest of the Prussians before conquering and converting the Lithuanians in the subsequent decades . The order also came into conflict with the Eastern Orthodox Church of the Pskov and Novgorod Republics . In 1240 the Orthodox Novgorod army defeated the Catholic Swedes in the Battle of the Neva, and, two years later, they defeated the Livonian Order in the Battle on the Ice . </P>

Who fought for control of the holy land during the crusades