Jean 1 de Grailly was an exceptional warrior and administrator under Kings Henry III and Edward 1. He was Seneschal of Gascony and also, following his crusade, Seneschal of Jerusalem. Later Jean III de Grailly (his great-grandson) achieved notable distinction serving with Edward, The Black Prince. Eventually he was captured and imprisoned. Offered freedom if he swore loyalty to the King of France, he refused, preferring to die in prison, which he did.
The Grailly family acquired the name, titles and substantial lands of de Foix family through the marriage of Archambaud de Grailly to Isabelle de Foix in 1380. Archambaud’s son, Gaston de Foix married Marguerite d’Albret. Gaston was in turn a loyal warrior and administrator for Kings Henry V and Henry VI. He was proxy for Henry V for Henry’s formal marriage to Catherine de Valois, and was elected a Knight of the Garter.
Gaston’s son Jean de Foix (Tree 1) was to prove no less capable. His ties to England were made all the more secure by his marriage in 1446 to Margaret Kerdeston. Margaret was the daughter of Sir Thomas Kerdeston and Elizabeth de la Pole. Margaret had a sister who married Robsart and probably another who married a Berkeley. (Thanks to Douglas Richardson for sorting this out!) This connection to the de la Poles was important since William de la Pole, Elizabeth’s brother, was the Duke of Suffolk and he wielded considerable influence over King Henry VI and his wife Margaret d’Anjou.