He was summoned by writ to parliament in 1388, and became active in public affairs following the succession of Henry IV to the throne.

He was engaged in Anglo-Scottish diplomacy and took part in the Battle of Humbleton Hill in 1402 and in the negotiation of the surrender of his uncle, Richard le Scrope, Archbishop of York, in 1405.

He participated in the Battle of Agincourt in 1415 and subsequent diplomacy with the French, which led to the Treaty of Troyes in 1420.

In the next generation the FitzHugh family thenceforth quartered the arms of Marmion and St Quentin, as shown later in the arms of Queen Catherine Parr and later still by Herbert, Earls of Pembroke, visible in Wilton House.

By his wife he had eight sons and six daughters, including:[5] He died on 11 January 1425 and was buried in Jervaulx Abbey in Yorkshire, as he requested.