He joined the Royal Navy at the age of 13 and served in it for 12 years. On his return to Scotland he was persuaded to join his father in the 1715 Jacobite rising and took part in the inconclusive Battle of Sheriffmuir. After the suppression of the uprising he was forced to hide for some time in a secret chamber at the nearby castle of Newark until his aunt secured him a pardon. He then joined the army of George I and fought in the War of the Austrian Succession, being present at the Battle of Dettingen in 1743, and the Battle of Fontenoy in 1745.