Sir John was killed in 1636 and succeeded as Colonel by his brother George, then, after his death in 1637, Lord James Douglas; following the custom of the time, the unit became known as the Régiment de Douglas. James died in a skirmish near Douai in 1645 and was replaced by his elder brother Archibald Douglas, Earl of Angus, who remained in Scotland and had little contact with the regiment, other than supplying recruits. In 1653, he assigned the Colonelcy to his younger half-brother, George Douglas, later Earl of Dumbarton.