did he also participate in a war?
Yes, Hundred Years' War.
John FitzWalter, 2nd Baron FitzWalter
FitzWalter was summoned alongside 43 other Essex knights to muster in Ipswich in December 1338.
who was john fitzwalter? A prominent Essex landowner best known for his criminal activities, particularly around Colchester. where was he born? UNANSWERABLE was he a part of any service? Yes, Royal service what was his role there? soldier
wiki:9461731
John FitzWalter, 2nd Baron FitzWalter [SEP] Royal service and war in France
Diplomatic relations between England and France had been tempestuous for some years, and in 1337 crisis broke out when the king of France, Philip VI, confiscated the Duchy of Aquitaine, then a possession of English kings. In response, King Edward invaded France, thus beginning the Hundred Years' War. Harris has described the young men of FitzWalter's class and generation as being "untapped pools of genteel manpower", manpower which the King was determined to exploit. FitzWalter was summoned alongside 43 other Essex knights to muster in Ipswich in December 1338. Armed and ready to fight, FitzWalter joined the retinue of William de Bohun, who had recently been created Earl of Northampton.