The Seljuk Turks tortured Christians in Asia Minor brutally and destroyed christian relics. When the Turks besieged Constantinople, Byzantium's emperor wrote a letter to Pope Urban II about the destruction and torturing of the Christians. Pope Urban II told the Catholic Kingdoms to join arms and defeat the Islam, so Catholicism could regain the Holy Places, slow down torturing of Christians, and if they didn't help Byzantium in time, MANY of Christianities most sacred relics would be gone forever. The first crusade was a success, and Catholics held it for decades, making two major kingdoms- The Principality of Antioch, and The Kingdom of Jerusalem. Later crusades failed, some because of Generals not coming their alive (like the Holy Roman Empire's Emperor Barborossa), and some, unfortunately, because of sin (like Venice's Sacking of Constantinople).
Because the Popes lost the support of the gentry who was crusading. That, coupled with the failures of each Crusade and the inability to hold anything in the Holy Land for any period of time.
Crusades
The Crusades were started because the the Muslims, Christians, and Jews all share the Holy Land of Israel, and the first crusade occured because the Christians were trying to recapture the holy land.
The Crusades were an attempt by the Christian States to retake the Holy Land from the Muslims, who had invaded an captured it.
Conquest of large areas of Palestine
The Crusades were a series of Holy Wars between Christians and Muslims over 'the Holy Land' in medieval Europe.
The chief goal was to rescue the Christian Holy Land or Jerusalem from the Saracens.
The Crusades were about re-capturing the Holy Land, which is the sacred land for Christians.
Urban II opened the First Crusade. Other Popes encouraged other Crusades, seven or eight in all.
Because the Popes lost the support of the gentry who was crusading. That, coupled with the failures of each Crusade and the inability to hold anything in the Holy Land for any period of time.
In the Holy land e.g. Jerusalem
the crusades were to rescue christian holy items and land the first was to regain the holy land the others were to storm places were they belived the arabians were hiding the holy grail and such.
The mission of the Crusades was to take over the Holy Land (Jerusalem).
Christian military expeditions to take the "holy land" from the Muslims during the middle ages were called crusades becasue they carried the Sign of the Cross before them.
Crusades occurred mostly to regain the Holy Lands - The Kingdom of Jerusalem from the muslims.
The Muslims controlled the Holy Land after the crusades ended.
Prior to the crusades, the Holy land had been taken over by Muslims. The crusaders went to the Holy Land to fight the Muslims and kick them out.