Treaty of Ceprano (1080)

The Treaty of Ceprano, signed in June 1080, was an agreement between Pope Gregory VII and Robert Guiscard, the Norman Duke of Apulia and Calabria. It marked a significant shift in the relationship between the papacy and the Normans in Southern Italy.

Prior to the treaty, the Normans had been a source of considerable trouble for the papacy, expanding their territories and challenging papal authority. Gregory VII, struggling with the Investiture Controversy against Holy Roman Emperor Henry IV, had previously excommunicated both Henry IV and Robert Guiscard.

However, the siege of Rome by Henry IV in 1080 forced Gregory VII to seek assistance from the Normans. Robert Guiscard, motivated by political expediency and the desire for papal legitimization of his conquests in Southern Italy, agreed to come to Gregory's aid.

The Treaty of Ceprano resulted in the formal recognition of Robert Guiscard's control over Apulia, Calabria, and Sicily (although the Normans did not yet control the entire island of Sicily). In return, Robert Guiscard swore an oath of fealty to Pope Gregory VII and promised to defend the papacy against its enemies, most notably Henry IV.

The treaty effectively secured Norman military support for Gregory VII, which proved crucial in relieving the siege of Rome. While the alliance was beneficial in the short term, it also had long-term implications. The Normans, now officially sanctioned by the papacy, continued their expansion in Southern Italy, eventually establishing the Kingdom of Sicily, which became a significant power in the Mediterranean. The alliance also helped to define the political landscape of Italy for centuries to come.