Italy with his friend John Angerstein, becoming an accomplished linguist. On his return, through his interest with the Duke of York he was brought into the 52nd light infantry, and after spending a few months in England joined his regiment at Halifax, Nova Scotia, in the autumn of 1823. In 1824 he went on detachment duty to New Brunswick and Prince Edward Island, and in the spring of 1825 was hastily summoned to Quebec to see his father, but the bishop died some days before he arrived. Mountain brought his mother and sister to England in October. He purchased a company in the 76th regiment and was gazetted captain on 26 May 1825. Joining the regiment in Jersey in the spring of 1826, he won the friendship of the governor, Sir Colin Halkett, through whose influence and that of Sir Astley Cooper he obtained an unattached majority on 30 Dec. 1826.
For the next two years he was unemployed, and resided with his mother at Hemel Hempstead, Hertfordshire, amusing himself with translating some of Schiller's poems and in writing the life of the Emperor Adrian for the 'Encyclopaedia Metropolitana.' In December 1828, through the influence of his friend Lord Dalhousie, he was brought into the 26th Cameronians, then stationed at Madras, as regimental major, and in the following May he sailed for India. He arrived at Fort George in September and remained in Madras until the autumn of 1830, when the regiment marched to Meerut, arriving in March 1831. In July Mountain visited Lord Dalhousie, then commander-in-chief in India, at Simla, and in October marched with him back to Meerut. While visiting Lord William Bentinck, the governor-general, at Delhi, Mountain accepted from his old friend Sir Colin Halkett, who had just been appointed commander-in-chief at Bombay, the appointment on his staff of military secretary, and arrived in Bombay on 21 March 1832. Owing to differences with the governor, Lord Clare, Sir Colin Halkett was recalled towards the end of the following year, and Lord William Bentinck, appreciatingthe discretion with which Mountain had acted, appointed him one of his aides-de-camp. In August 1834 he obtained leave to join a force assembled at Meerut to march to Shehkawattee under General Stevenson, and rejoined the governor-general at Calcutta at the end of December, after a journey of nearly four thousand miles. In March 1835 he left for England with Lord William, and spent the next two years at home. In July 1836 he declined the post of military secretary to Sir Samford Whittingham in the West Indies. In February 1838 he rejoined the Cameronians at Fort William, Calcutta.
In 1840 the China war broke out, and Mountain was appointed deputy adjutant-general to the land forces sent from India, first under the command of Colonel Burrell and afterwards under Sir Hugh Gough. He was present at all the chief engagements, including the capture of Tinghae on 5 July, and of the Bogue forts 26 Feb. 1841, at the attack on, and capitulation of, Canton 25 May, capture of Amoy 26 Aug., occupation of Chusan, 1 Oct., capture of Chin-hai 10 Oct, and of Ning Po 13 Oct., attack on Chapoo 18 May 1842, capture of Shanghai 19 June, of Chin Keang 21 July, and the demonstration before Nankin in August which led to the treaty of peace. At the attack on Chapoo Mountain was struck by three musket balls while making a gallant rush into a large building defended with great obstinacy by the enemy. He was made a C.B. for his services.
From China he returned to India early in 1843, took command of his regiment and brought it to England, arriving in June. For the next four years he commanded the regiment at various stations in the United Kingdom and Ireland. In June 1845 he received his promotion to colonel in the army on being appointed aide-de-camp to the queen for his services in China.
In August 1847 Lord Dalhousie, then governor-general of India, gave him the appointment of military secretary, and he arrived in India in January 1848, having exchanged into the 29th regiment. After the murder of Anderson and Vans Agnew at Mooltan, Mountain obtained leave to join his regiment to take part in the second Sikh war under his old chief, Lord Gough. He was made a brigadier-general, and his brigade was composed of his own regiment and the 13th and 30th native infantry. On the death of Colonel Cureton the post of adjutant-general was accepted by Mountain on the condition that he should retain his brigade until the approval of his nomination arrived from home. He took a prominent part in the battle of Chillianwalla on 13 Jan. 1849. Lord Gough in his despatch says: 'The left brigade, under Brigadier Mountain, advanced under a heavy fire upon the enemy's guns in a manner that did credit to the brigadier and his gallant brigade, which came first into action and suffered severely.' He also took part in the battle of Guzerat on 21 Feb., and was afterwards appointed to command the Bengal division of the force under Sir Walter Gilbert to pursue the
