Excommunication of Frederick II

Background

Under the San Germano agreement Frederick II would be excommunicated if he did not depart on crusade in August 1227. In summer 1227 a large crusader army gathered at Brindisi, but disease broke out in the hot, crowded camp. Gregory IX, elected pope in March 1227, took a much harder line toward the emperor than Honorius III.

Course of events

Frederick set out from Brindisi on 8 September 1227, but he and Landgrave Louis of Thuringia, who was with him, fell ill. Louis died at Otranto. Frederick went back to the baths at Pozzuoli to recover and sent part of the army to Acre with Hermann von Salza.

Gregory IX regarded the emperor's illness as a pretext and excommunicated him at Anagni on 29 September 1227. The pope accused the emperor not only of postponing the crusade but also of his conduct toward the church in Sicily.

Outcome and significance

Frederick did not accept the excommunication and set out for the East excommunicate in June 1228. This created an unprecedented situation: a ruler under church censure leading a crusade. In the emperor's absence the pope sent an army to attack Sicily.

The excommunication began the great conflict between the papacy and the Staufen dynasty that lasted until the mid-thirteenth century, extending even to the use of crusade taxes and privileges against the empire.

Sources and debates

Papal letters explain the grounds for the excommunication in detail; Frederick's letters to the rulers of Europe stress his illness and the papacy's injustice. Richard of San Germano and Matthew Paris report the events from different perspectives. Whether the emperor's illness was real is debated, but the epidemic and Louis's death are certain.