"Result:  bitter conflict between Pope Gregory VII (1073-1085) and Henry IV (1056-1106):  the Investiture Controversy (1074-1122)—at its height, the Pope banned lay investiture and threatened Henry with ex-communication; Henry tried to depose the Pope, who promptly excommunicated him and released his subjects from any allegiance to the emperor. Henry's lords rebelled & forced him to make peace at Canossa (1177).  Struggle finally ended by the Concordat of Worms (1122):  the Emperor lost the right to appoint bishops while retaining the right to grant them land and secular political power.  The Church won the Investiture Struggle, and in doing so it weakened the Holy Roman Empire, thus permitting the growth of feudalism and greater power for the feudal lords." This is a perfect example of the pope's power. How did the pope gain and continue to exercise it's power at this time?
http://www.uncp.edu/home/rwb/lecture_mid_civ.htm