The Corbet brothers followed Arundel to Normandy in August 1415 as part of the king's pursuit of his claim to the French throne. However, the earl contracted dysentery at the Siege of Harfleur only a month after the start of the campaign and was invalided home to Sussex, followed by Robert Corbet. The earl died at Arundel Castle on 13 October, leaving the Corbets without a protector. Roger seems to have remained in France and there is no evidence that he left before the Battle of Agincourt, so he very well could have been a participant.