Frederick II is excommunicated as his conflict with the papacy escalates
A brilliant, unconventional emperor spends much of his reign at war with Rome
Quick facts
- Territory
- Holy Roman Empire and Kingdom of Sicily
- Nickname
- Stupor Mundi, 'Wonder of the World'
- Excommunicated by
- Gregory IX (1227, 1239), Innocent IV (1245)
- Reign
- 1220-1250 (as emperor)
What happened
Frederick II, Holy Roman Emperor and King of Sicily, ruled territory on both sides of the Papal States, north in Italy and Germany, south in Sicily, a geography that made every pope of his reign fear encirclement. Contemporaries called him Stupor Mundi, 'wonder of the world,' for his multilingual court, scientific curiosity, and religious skepticism. Pope Gregory IX excommunicated Frederick for the first time in 1227 over a delayed crusade, then again on Palm Sunday, 20 March 1239, drawing up formal charges against him. Frederick answered by denouncing the papacy's worldly corruption and calling the pope 'a wolf in a sheep's clothing.' His successor, Pope Innocent IV, excommunicated and formally deposed Frederick again in 1245, going so far as to brand him forerunner of the Antichrist.
Why it matters
The Frederick-papacy conflict was the most extreme phase of the long empire-versus-papacy struggle that had begun with the Investiture Controversy, and though the papacy survived it, the toll of fighting a Christian emperor with spiritual weapons exhausted papal authority in ways that contributed to its later diminishment under the Avignon popes.
How we know
The excommunications and Frederick's responses are documented in papal correspondence and in the imperial chancery's own records defending his position, both of which survive from his reign.
Sources
- World History Encyclopedia. Frederick II · Reputable sourceworldhistory.org · The domain "worldhistory.org" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
- World History Encyclopedia. Frederick II · Reputable sourceworldhistory.org · The domain "worldhistory.org" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
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