Gaston I de Foix-Grailly

Through the marriage of Gaston's father, however, to the heiress of the Count of Foix, Matthew, and in response to military pressure, the family became subject to the King of France by the Treaty of Tarbes.

In accordance with this treaty, Gaston and his elder brother, John, were sent to the royal court at Paris as hostages, to guarantee the loyalty of their parents and to receive a proper education.

Gaston took part in the victorious Battle of Agincourt on 25 October of the same year, while his brother, John I, Count of Foix, fought for the other side.

When the balance of the war changed in favour of France with the rise of Joan of Arc, Gaston's lands in Gascony also fell into the hands of the French.

Nonetheless, Gaston refused to recognize the Treaty of Pons on 12 June 1451, which governed the relationship between the French crown and the Gascoigne nobility, and denied his homage to Charles VII of France.