In the rebellion of the Earl of Lancaster in 1322, he brought forces to the aid of King Edward II and, after the defeat of the rebels at Boroughbridge, took part in the defence of northern England against Scots invaders.

After fighting the Scots again at Halidon Hill in 1333, he ceded his inheritance from his uncle Robert Mohaut to the Queen Mother Isabella keeping only some lands in Suffolk.

[1] As the government faced war with France and Castile, to his civil duties in Norfolk were added responsibilities for defence and he was not part of England's invasion forces in 1338.

After fighting off a French offensive on the Cinque Ports, he mounted successful attacks on the coast of Normandy, followed in 1340 by leading the English fleet to victory at Sluys.

[1] Reassigned to coastal defence of Norfolk in 1451, as a judge for the county he was responsible in 1354 for enforcing the Statute of Labourers, which attempted to regulate wages after the Black Death.