In 1793, he was promoted major-general, and was appointed colonel of the newly formed 81st Regiment of Foot on 19 September with instructions to recruit volunteers for it. In 1794, he obtained a colonelcy of an existing regiment, the 9th (East Norfolk) Regiment of Foot, instead. Bertie was promoted lieutenant-general in 1798 and general in 1803. In 1804, the Duke of York recommended him for the colonelcy of the 77th Regiment of Foot, then part of the Indian establishment, noting that "the difference of emolument is of great consequence" to Bertie. In 1808, he became commander of the 89th Regiment of Foot after John Whitelocke was cashiered and dismissed from the service.