In 1706 Jean started a 39 year Military career as an Ensign with Earl of Barrymores's 13th Foot Regiment. by 5th April 1739 he was a Captain with Brigadier-Gen H. Pultney's Regiment, and was part of the Allied forces , under the Duke of Cumberland, against 50 thousand French in 1745 when he was killed in Action at the Battle of Fontenoy, which was the blodiest battle in Western Europe since 1709. French losses were estimated at 7,000 to 8,000 killed and wounded and those of the Allies between 7,400 and 12,000, including prisoners.
