In July 1338, Hugh sailed from Orwell with the king's army to Antwerp in the Duchy of Brabant. He took part in the naval campaign in the English Channel and was present at the battle of Sluys on 24 June 1340. In 1342–43, he served in the "comitiva" (retinue) of the Earl of Pembroke during the Breton campaign. He was serving under the Earl of Pembroke again during the Aquitanian campaign of 1345, under the ultimate leadership of the Earl of Derby. According to the French chronicler Jean Froissart, Hugh was present for Derby's victory in the battle of Auberoche on 21 October 1345. It is known, however, that the Earl of Pembroke missed the battle and so it is possible that Froissart is mistaken in placing Hugh there. Hugh appears to have returned to England before the Siege of Aiguillon, which lasted from April to August 1346 and resulted in England retaining control of the castle.