In the early Middle Ages, a feudal system provided law and order. The manorial system dominated medieval life. In the Middle Ages, there were two rankings in specific that didn't get along well. The highest ranking was the Pope. The second highest ranking was the King. These two cooperated but at the same time had conflicts.
Your excommunicated from here!
In 1073, a monk named Hildebrand became Pope Gregory VII. Gregory had strong ideas about the Pope, and issued a list of rules declaring his supreme authority over both Church and secular, or non church. Gregory decided that the pope alone had the power to choose bishops. He even claimed to have the powers to remove the emperors from their throne.
I bet I have WAY more people than him.
People are taking sides...
Henry IV, the Holy Roman Emperor at the time, reacted to this rule change, and felt as if this were a direct attack on his power and rights. This let to conflict between both pope and emperor. The clash began when Henry ignored the pope's rules and named his own bishop for the city of Milan, Italy. In response, Pope Gregory appointed a rival bishop.
I will beat him!
I will win!
Next, Henry tried to remove Gregory as pope. Pope Gregory then excommunicated Henry, or excluded him from a church or religious community. The pope freed Henry's subjects from their feudal oaths of loyalty to the emperor.
Members of the clergy and secular rulers started taking sides across Europe. The power struggle between popes and rulers continued long after Gregory and Henry died. Eventually, in 1122, the Church and Holy Roman Empire reached an agreement called the Concordat of Worms.
This agreement gave the Church the sole authority to appoint bishops. But it also allowed emperors to give fiefs, or grants of land to bishops in order to win their loyalty. Despite this agreement, popes and rulers continued to have conflicts.