Later that year he entered the service of Henry of Bolingbroke, Earl of Derby, and in 1390 went on his expedition to Prussia, fighting with the Teutonic Knights at Vilnius against the forces of the Grand Duke of Lithuania.
In 1415, with a small force, he joined the expedition of King Henry V to France and after its capture was part of the garrison of Harfleur.
[1] From his father he inherited small properties in Devon, including Challonsleigh and the manors of Buckerell and Awliscombe, which yielded only about 5 pounds a year.
[1] On his marriage, Duke Henry awarded the couple an income of 20 marks (over 13 pounds) from the manor of Brecon.
These were however gradually lost to legal and illegal challenges by Sir Robert Cary and associates so that by 1445 he held none.
[1] After the death of his father-in-law in 1409, he and his wife received 400 marks (267 pounds) as their share of his wealth, together with a part of the manor of Eaton Tregoes in Foy, Herefordshire.