Many of the Holy Roman emperors had serious conflicts with the Popes in Rome. In the investiture controversy, which I wrote about before, Pope Gregory VII and Henry IV quarreled over the authority of the church. But, the conflict did not stop there. The Holy Roman emperors brought forth opposition to the Popes once again under Frederick Barbarossa, who was the Holy Roman emperor from 1155-1190. He strove for centralization in the German lands, but was in need of money to do so. To get this money, he decided to attempt a conquest of Lombardy and to acquire its wealth. With all of this money, he hoped to exert his power over all of the German lords. He also thought that if his empire was going to be like the Roman empire of old, he needed to have Italy too.
The Lombard cities did not accept this, making an alliance with Pope Alexander III and with each other, forming the Lombard league. The Pope was fearful of the imperial power and would not accept the authority of the various antipopes Frederick supported who would do his bidding. Frederick burned the city of Milan to the ground during his campaign, but =was eventually defeated by the Lombard league. Frederick was forced to submit, and the emperor and pope reconciled to each other. Frederick arranged a marriage between his son and the future heiress of southern Italy and Sicily, surrounding the papacy with imperial possessions.
Not long after Barbarossa died in 1190, two families, the Hohenstaufens (Frederick’s family) and the Welfs, put forward candidates for the position of emperor. The Welf Candidate, Otto, promised to obey the wishes of the church. Pope Innocent III supported Otto, and he was crowned emperor in the year 1209. Otto, however, broke his promises to the pope and invaded southern Italy. Innocent declared him deposed and supported the Hohenstaufen candidate, Barbarossa’s son Frederick II. Innocent got Frederick II to make key promises, including giving up his claims to Sicily, following the direction of the papacy, and leading a crusade. Otto’s claim crumbled after a failed invasion of France, and Frederick II became the emperor.
Frederick became the ruler of both the Holy Roman Empire and Sicily, but went back on his promises and united the two domains into one. He also intended to incorporate all of Italy into the empire. He also continued to make unfulfilled pledges to lead a crusade. Frederick plundered Italian sees, monasteries and hospitals when he tried to add more of Italy to his empire.
In 1227, Pope Gregory IX excommunicated Frederick, but said he was merciful for not calling on him to give up Sicily. Frederick denounced Gregory for this, and began stirring up opposition to him. In 1239, Gregory issued another excommunication along with an interdict on any lands he travelled in. Frederick responded by expelling all friars from Sicily and threatening to hang anyone who brings a papal document into Sicily. Gregory calls for a council in 1241, but died in the same year. In response Frederick ordered the arrest of all bishops travelling to the council.
Gregory was succeeded by Celestine IV, who died a few months later. He was succeeded by Innocent IV, who ,after attempts at negotiation, decided to take action against Frederick. Innocent convened a council at Lyons, where Frederick was declared deposed as emperor. Frederick tried to influence other European monarchs to get rid of Innocent, but died in 1250.
The conflict between the popes and the Holy Roman Emperors arose because of land claims in Italy, authority over the church, and the unchristian behavior the popes saw in the emperors. The popes also wanted to stay safe from the emperors, who might threaten to subject the papacy to their control. The popes saw their authority challenged by the rival claims supported by Frederick Barbarossa and by the desire of Frederick II to bring Italy under his rule.