Sometime in the 11th century, Muslims who had become quite powerful, invaded the lands of the Byzantine empire including the Holy Land. These Muslim Seljuks threatened the main heartland of the Byzantine empire to which the emperor responded by asking for help from the rest of Christendom.
In response, Pope Urban II appealed to the European states for help. The People's Crusade ensued which saw many lower class citizens from across Europe march to the east. Poor equipped and lacking in training, they were massacred by the Muslim armies.
Their place was taken by soldiers led by nobility and they achieved great victories against the Muslims.
