Treaty of Benevento

 After the Normans conquered Sicily, they had a hard time holding on to it. In 1155, Byzantine Emperor Manuel Comnenus reconquered parts of the southern Italian mainland. For Pope Adrian IV (the only English pope to date), having the Byzantines on its southern border was preferable to the troublesome Normans. In an alliance with Manuel, Adrian undertook to raise a body of mercenary troops to war against the Normans. But just as the war seemed decided in the allies' favor, things started to go wrong. The Greek commander, Michael Palaeologus, was recalled to Constantinople. He was a brilliant general in the field, and his loss was a major blow to the allied campaign. The turning point was the battle for Brindisi, where the Sicilians launched a major counterattack by both land and sea. At the approach of the enemy, the mercenaries deserted. Soon Adrian's Byzantine allies were left hopelessly outnumbered. William and his army landed on the peninsula and destroyed the Greek fleet (4 ships) and army at Brindisi on May 28, 1156. The Sicilian army approached Benevento where the pope was in residence, and the pope was forced to make terms, signing the Treaty of Benevento confirming William as king on June 18, 1156.

The kingship of William I of Sicily (William the Bad, 4^th son of Roger II) was recognized over all Sicily, Apulia, Calabria, and Campania, as well as Capua, the coastal cities of Amalfi, Naples, and Gaeta, and the newly conquered territories of Marche and the Abruzzi. The pope had to resign much claimed authority over the island. In the church of S. Marciano, William was invested by the pope with first Sicily, then Apulia, and finally Capua. In return, William paid tribute to the pope of 1000 schifati (similar to the Byzantine gold solidus).