In July 1436 Oxford mustered his retainers at Sandwich, Kent for an expedition to relieve the Siege of Calais by the Duke of Burgundy. On 23July 1437 he was summoned to attend the funeral of Queen Joan at Canterbury. In June 1439, with Cardinal Henry Beaufort and other envoys, he was appointed a commissioner to treat of peace with France. On 16May 1441 he sailed from Portsmouth to France with Richard Plantagenet, 3rd Duke of York, who had been appointed Lieutenant-General and Governor of France and Normandy. In June 1450 Oxford was among the noblemen appointed to act against Jack Cade's Kentish rebels.