The First Crusade was launched in by Pope Urban II , with the stated goal of regaining control of the sacred city of Jerusalem and the Holy Land from the Muslims, who had captured them from the Byzantines in It was also partly a response to the Investiture Controversy , which was the most significant conflict between secular and religious powers in medieval Europe.
The controversy began as a dispute between the Holy Roman Emperor and the Gregorian Papacy and gave rise to the political concept of Christendom as a union of all peoples and sovereigns under the direction of the pope; as both sides tried to marshal public opinion in their favor, people became personally engaged in a dramatic religious controversy.
Also of great significance in launching the crusade were the string of victories by the Seljuk Turks, which saw the end of Arab rule in Jerusalem. Capture of Jerusalem by the Crusaders in On 7 May the crusaders reached Jerusalem , which had been recaptured from the Seljuks by the Fatimids of Egypt only a year before.
On 15 July, the crusaders were able to end the siege by breaking down sections of the walls and entering the city. Over the course of that afternoon, evening and next morning, the crusaders killed almost every inhabitant of Jerusalem.
Muslims and Jews alike. Although many Muslims sought shelter atop the Temple Mount inside the Al-Aqsa Mosque , the crusaders spared few lives. According to the anonymous Gesta Francorum , in what some believe to be one of the most valuable contemporary sources of the First Crusade, " According to Fulcher of Chartres: "Indeed, if you had been there you would have seen our feet coloured to our ankles with the blood of the slain.
