Acheson has also suggested that it was probably Ferrers' direly unstable financial situation that led him to seek a career in royal service, as the King had started a new war with France. Ferrers accompanied the Black Prince to Gascony in 1355. fought at the Battle of Crecy in 1355, at Poitiers the following year, and was with Henry of Grosmont, 1st Duke of Lancaster in the 1359–60 Reims campaign. Ferrers last served in France in 1369, again with Lancaster, raiding Picardy and Caux that July.