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Why did Philip IV of France go to war with England over Gascony?

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King Philip IV — Philip IV Philip IV, detail of the statue from his tomb, 14th century; in the abbey church at Saint-Denis, France.

Philip IV of France engaged in war with England over Gascony primarily due to long-standing tensions regarding administrative rights and the feudal relationship between the two crowns. As the English kings held Gascony as vassals of the French monarch, the French administration frequently intervened in the duchy's affairs, encouraging local appeals to the Parlement of Paris, which strained relations.123

The conflict escalated in 1293 following violent clashes between French and English seamen. Philip IV demanded compensation and summoned his vassal, Edward I of England, to appear before him. When Edward failed to comply and Gascon castles were not returned as expected, Philip declared the duchy of Gascony confiscated in 1294, prompting Edward to renounce his homage and prepare for war.132

While the war was driven by these jurisdictional and feudal disputes, historians also note that Philip’s decision may have been influenced by a desire to demonstrate his power over his mighty vassal. The resulting conflict lasted until 1303, when a peace treaty was established.21