Treaty of Orvieto

Intended to restore Latin domination, both civil and ecclesiastical, to Greece, it was forestalled by the War of the Sicilian Vespers, which diverted the resources of Charles to the recovery of Sicily.

A younger brother of the French king, Louis IX, he had enlarged his appanage of Provence by agreeing to act as the Papal champion against the Hohenstaufen in 1263.

Under Pope Gregory X, negotiations for the union of the Roman Catholic and Greek Orthodox Churches were initiated, and any move by Charles against Constantinople was forbidden.

Like the Treaty of Viterbo, the new alliance against Constantinople would unite the arms of Charles and the dynast of the Latin Empire (now Philip of Courtenay, Baldwin II having died in 1273) under Papal sanction.

Furthermore, the Venetians, who had played a key role in the Latin Empire but had not subscribed to the Treaty of Viterbo, were also to be brought into the alliance.

Its practical motivation, however, was to re-establish the Latin Empire, under Angevin domination, and to restore Venetian commercial privileges in Constantinople.

These forces would make war against Michael VIII and "other occupiers" of the Latin Empire (presumably the Genoese), and would meet at Corfu by 1 May 1282, paving the way for the next year's invasion.

His descendants would continue to maintain an ever more tenuous rule over parts of the Latin Empire, but no grand expedition against Constantinople was ever mounted.