[1] His reign began at the age of 14 in 1157, while he acted as regent and co-count for his father, who had returned to the Kingdom of Jerusalem in 1156 after participating the Second Crusade.

[2] He defeated Count Floris III of Holland, who was captured in Bruges and remained in prison until 1167, at which point he was being ransomed in exchange for recognition of Flemish suzerainty over Zeeland.

This pushed Flemish authority further south, to its greatest extent thus far, and threatened to completely alter the balance of power in northern France.

In 1175, Philip discovered that Elisabeth was committing adultery and had her lover, Walter de Fontaines, beaten to death.

Philip's brothers Matthew and Peter of Alsace also died in 1177, before going on crusade, he designated Margaret and Baldwin as his heirs.

In the Holy Land, King Baldwin IV of Jerusalem hoped that Philip would take part in a planned invasion of Egypt, for which purpose the crusaders had allied with the Byzantine Empire.

Baldwin IV was a leper and childless, and offered Philip the regency of the Kingdom of Jerusalem as his closest male relative currently present there.

Philip left Jerusalem in October to campaign in the north for the Principality of Antioch, participating in an unsuccessful siege of Harim before returning home.

Despite a costly war, the economic expansion of Flanders did not stop, as witnessed by the number of communal charters signed by Count Philip.

[9] In the opening lines, Chrétien honours Philip with "excessive praise" (Roach, Frappier, Hilka, et al.) for providing him with the book he adapted into the "best tale ever told in a royal court".