The War of the Keys

The War of the Keys was called that because of the image of crossed keys (keys to the Kingdom of Heaven) on the papal flag. The war was between Pope Gregory IX and Holy Roman Emperor Frederick II. Frederick vowed to go on Crusade, which Gregory supported wholeheartedly. The vow was on pain of excommunication. Gregory's predecessor, Honorius III, had granted Frederick several delays, but Gregory was not going to be patient anymore, and threatened Frederick with excommunication.

Along with that issue, Frederick laid claim to some lands in central Italy that the popes believed belonged to the Papal States. Also, Gregory felt that Frederick was abusing the church in Sicily.

Part of Frederick's agreement to go on Crusade was that he wanted to be King of Jerusalem. Currently, the King-by-marriage was John of Brienne, who was regent for his 12-year-old daughter, Queen Isabella II of Jerusalem. The marriage, in November 1225, removed John's regency and made technically Frederick King of Jerusalem. Yet still he delayed.

Gregory excommunicated Frederick in October 1227. Isabella died in May 1228. In June 1228, Frederick finally began the Sixth Crusade. While he was traveling, some of his followers invaded the disputed Italian territories. Gregory responded with an army intending to take Sicily from Frederick. For the leader of his army he chose John of Brienne. Gregory levied tithes from several Christian countries to raise money for his army. According to contemporary English chronicler Roger of Wendover, England resisted the tax. King Henry III of England called an assembly of nobles and prelates to hear from the papal legate about the tithe, but the nobles simply refused to pay. Henry did not do anything to interfere with the papal request, but he did not force his nobles to comply.

Meanwhile, Frederick was in the east and signing a treaty with al-Kamil, who was perfectly happy to giving Jerusalem to the Crusaders if they left him alone. When Gregory heard about this, he denounced the treaty and Frederick as being un-Christian.

Now, however, Frederick was free to return and face the pope's forces. We will see how that went tomorrow.