Thomas was opposed to Richard II's desire for peace with France in the Hundred Years' War and a power struggle ensued between him and Gloucester.

[1] As Admiral of England, he defeated a Franco-Spanish-Flemish fleet off Margate in March 1387, along with Thomas de Mowbray, Earl of Nottingham.

[5] In August 1387, the King dismissed Gloucester and Fitzalan from the Council and replaced them with his favourites—including the Archbishop of York, Alexander Neville; the Duke of Ireland, Robert de Vere; Michael de la Pole; the Earl of Suffolk, Sir Robert Tresilian, who was the Chief Justice; and the former Mayor of London Nicholas Brembre.

[4] He made himself particularly odious to the King by refusing, along with Gloucester, to spare the life of Sir Simon de Burley who had been condemned by the Merciless Parliament.

[1] By 1394, Arundel was again a member of the royal council, and was involved in a quarrel with John of Gaunt, whom he accused in the parliament of that year.

Richard II, in a rage, snatched a wand and struck Fitzalan in the face and drew blood.

[1] Tradition holds that his final words were said to the executioner, "Torment me not long, strike off my head in one blow".

[12] In October 1400, the attainder was reversed, and Richard's son Thomas succeeded to his father's estates and honours.