During the Middle Ages, there were 164 popes officially recognized by the Roman Catholic church. The dates of the Middle Ages vary between sources but typically include at least the years between 500 to 1500 A.D.
As the church wielded political power across Europe during the Middle Ages, the deeds of a number of popes from that era may be considered of great historical significance. Nicholas II (c. 990 - 1061) instituted clerical celibacy. Leo III (c. 795 - 816) crowned the Emperor Charlemagne. Perhaps the best known pope of the Middle Ages was Urban II (c. 1088-1099), who called on all European Christians to remove Muslims from the Holy Land, initiating the Crusades.