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.

The Mamluk Sultanate of Egypt opens a dialogue with the revived Greek empire of Constantinople: the Greek sovereign orders the restoration of the ancient mosque and permits the Egyptian merchants and ambassadors to sail through the Hellespont and Bosporus.

The network of diplomacy laid by Michael VII Palaiologos covers the Il-Khanid Mongols of Iran and of the Golden Horde in Russia, as well as the Mamluks of Egypt.

Michael has fostered communication among the Hohenstaufen supporters in Sicily, the republic of Genoa, and finally and most important, King Peter III of Aragon, the son-in-law of the late Hohenstaufen King Manfred of Sicily, with whom the Greek emperor has formed a secret alliance against Charles d’Anjou, the expansionist monarch of Sicily and Naples.

The vast network of alliances erected by Charles to conquer the Greek East includes factions in Sicily, parts of Italy, Greek Laskarid dissidents, various Slavs of the Balkans, Philip of Courtenay of the former Latin Empire, France, and Venice, and the papacy.

The vast network of alliances erected by the expansionist Charles of Anjou to conquer the Greek East include not only Sicily, parts of Italy, Greek Laskarid dissidents, various Slavs of the Balkans, Philip of Courtenay of the former Latin Empire, France, and Venice, but also the papacy.

Charles invades imperial territory in 1281, launching an attack across the Adriatic on Berat in Albania under the French general Hugh “the Red” of Sully, a Burgundian a knight of fiery and haughty temperament.

According to the chroniclers, Hugh had been named Vicar-General of Charles' Kingdom of Albania in August 1279, and leads the Sicilian forces in their unsuccessful attempt to take Berat from the Empire in 1280–1281.

Sully is taken prisoner in an ambush in spring 1281, whereupon his army scatters and suffers many losses to the pursuing imperial forces.

He is then taken to Constantinople where he is paraded in the streets along with the other captives.

Sully will eventually be released after years in Greek captivity and return to Italy.

Philip and Beatrice have a daughter, Catherine (November 25, 1274 – October 11, 1307, Paris).

Philip dies in Viterbo in 1283.