In 1294, Edward I was essentially hoodwinked into giving up his remaining hereditary lands in France in exchange for a marriage to Philip IV's half-sister, either Blanche or Margaret, under the agreement that it would be restored later. But the French had no intention of giving Gascony back to Edward. In 1303, after Edward made several failed attempts to retake it, the Treaty of France restored Gascony to Edward and confirmed the betrothal of his son to Princess Isabella of France.
What if Philip IV had managed to hold onto Gascony? Any thoughts?