18 June Ross moved his troop to the rising ground on the right of the Chausée, placing two guns upon the Chausée. Between 11 and 12 A.M. the enemy advanced, directing their columns upon the heights on each side of the Chausée and upon a brow and village upon the right of Ross's position. Ross had two horses killed under him and one wounded. Three of his guns were disabled, and, when the enemy got possession of La Haye Sainte, it was no longer possible for the troop to hold its original position, and it took ground to its right. When the battle was won, with the three of his guns that still remained effective, Ross joined in the pursuit to the heights beyond La Belle Alliance. He halted with his troop for the night with the guards near La Belle Alliance, and marched the following day for Paris. He entered Paris with the allied army, and remained with the army of occupation until December 1815, when he returned to England. For his services in the Peninsula and at Waterloo he was made a knight-commander of the Bath and a knight of the Tower and Sword of Portugal; he received the second class of the order of St. Anne of Russia, medals for Busaco, Salamanca, Badajos, Vittoria, Nivelle, Nive, and Waterloo, and the war medal with three clasps for Fuentes d'Onoro, Ciudad Rodrigo, and Pyrenees.
Ross continued to serve with the ‘Chestnut’ troop, first at Lewes in Sussex, and then at Dublin and Athlone, until he was promoted to a regimental lieutenant-colonelcy on 29 July 1825. In 1823 he declined Wellington's offer of the post of brigade-major of royal artillery in Ireland. On his promotion to regimental lieutenant-colonel he was posted to the horse artillery, and in the autumn of 1828 he was, as a horse-artilleryman, appointed to command the royal artillery in the northern district, under Sir John Byng (afterwards Lord Strafford) [q. v.], who commanded the district. Ross resided at his own house near Carlisle, and Byng gave him a delegated command of the troops in the four northern counties of the district. In March 1828 Ross was appointed a magistrate for the county of Cumberland. For nearly sixteen years Ross held the delegated command of the troops in the north. The manufacturing districts were in a disturbed condition during most of this time, and the disaffection that prevailed entailed much responsible work. Ross had been promoted brevet colonel on 22 July 1830, and regimental colonel on 10 Jan. 1837, and was continued in the horse artillery. He was made a major-general on 23 Nov. 1841, a colonel-commandant of the twelfth battalion of royal artillery on 1 Nov. 1848, a lieutenant-general on 11 Nov. 1851, and a colonel-commandant royal horse artillery on 11 Aug. 1852. In April 1840 he was appointed deputy adjutant-general of artillery at headquarters, in succession to Sir Alexander Dickson [q. v.], and remained in this post until 2 May 1854, when he was appointed lieutenant-general of the ordnance, the master-general of the ordnance, Lord Raglan, having left the horse-guards for the Crimea. During Ross's tenure of office as deputy adjutant-general the horse artillery and field battery establishments were gradually placed on a more efficient footing, and many improvements were made in the means of instruction both for officers and men. Ross lent his hearty support to the Royal Artillery Institution, and was instrumental in the appointment of an officer at Woolwich as instructor of young officers of the royal artillery on first joining the service, an appointment which later developed into the department of artillery studies. On his initiation, classes were established at Woolwich for the instruction of officers in the various departments of the royal arsenal, a gun-practice range was made on Woolwich marshes, and about 1852 a small station for artillery was formed at Shoeburyness for experimental practice, which has since developed into the school of gunnery.
To Ross fell the duty of preparing the force of artillery to be sent to the Crimea; and he had the satisfaction of seeing every battery and every portion of a battery shipped from England sent to its destination complete in itself and in a high state of efficiency. He was promoted general on 28 Nov. 1854, and carried on the duties of the appointment of surveyor-general of the ordnance until 22 May 1855, when arrangements were completed for amalgamating the ordnance and war offices, and the appointments of master-general and other offices of the board of ordnance were abolished. Ross was then placed on the staff of the commander-in-chief as adjutant-general of artillery, and continued at the Horse Guards in that appointment until his retirement on 1 April 1858.
Ross received the grand cross of the Bath on 19 July 1855. After quitting active employment he continued to reside in London. A public dinner was, on 9 March 1868, given to him and to Sir John Burgoyne, on the occasion of their promotion to the rank of field-marshal (1 Jan. 1868), by the officers of the royal artillery and royal engineers at Willis's Rooms, at which the Duke of Cambridge presided, as colonel of the two corps. On 3 Aug. 1868 Ross was appointed
