In 1324 when Edward II of England, in his capacity as Duke of Aquitaine, failed to pay homage to the French king after a dispute, Charles IV declared the duchy forfeit at the end of June 1324, and military action by the French followed. Edward sent his wife Isabella, who was sister to the French king, to negotiate a settlement. The Queen departed for France on 9 March 1325, and in September was joined by her son, the heir to the throne, Prince Edward (later Edward III of England). Isabella's negotiations were successful, and it was agreed that the young Prince Edward would perform homage in the king's place, which he did on 24 September and so the duchy was returned to the English crown.