Baldwin II of Constantinople had been forced to mortgage his young son, Philip of Courtenay, to Venetian merchants to raise money for the support of his empire, which was lost to the Empire of Nicaea in 1261.

By the Treaty of Viterbo in 1267, his father had agreed to marry him to Beatrice of Sicily, daughter of Charles I of Sicily and Beatrice of Provence.

Her maternal grandparents are Ramon Berenguer IV, Count of Provence and Beatrice of Savoy.

The marriage is performed in October 1273 at Foggia; shortly thereafter, Baldwin dies, and Philip inherits his claims on Constantinople.

Although Philip is recognized as emperor by the Latin possessions in Greece, much of the actual authority will devolve on the Angevin kings of Naples and Sicily.