was in command of the leading squadron of his regiment, and had a creditable encounter with the French light cavalry, on account of which he was recommended (unsuccessfully) for a brevet majority by Sir Stapleton Cotton. He was awarded the Peninsular Medal with two clasps. He served with the 15th Hussars in the campaign of 1815, in General Colquhoun Grant's brigade, which was on the right of the line at the Battle of Waterloo. He wrote of his experiences at Waterloo. After several engagements with the French cavalry at Waterloo, the regiment suffered severely in charging a square of infantry towards the end of the day. Thackwell had two horses shot under him and was wounded in his left arm, which was amputated the next day. He was promoted to the rank of major at Waterloo, and he was made brevet lieutenant-colonel on 21 June 1817. The regiment charged the crowd at the Peterloo massacre on 16 August 1819, at St Peter's Field in Manchester. He took command of the regiment in June 1820. After serving nearly 32 years in the regiment, and nearly 12 as its commander, he was placed on half-pay on 16 March 1832, exchanging with Lord Brudenell. He was made a Knight of the Royal Guelphic Order (KH) in February 1834. India Thackwell became a colonel in the army in January 1837, and in May 1837, by exchange, he took command of the 3rd The King's Own Dragoons, travelling with his new regiment to India and arriving in Calcutta in November 1837. He became local major-general and was placed in command of the cavalry of the Army of the Indus in the First Anglo-Afghan War of 1838–39. He was present at the Siege of Ghazni, and he commanded the second column of the part of the army which returned to India from Kabul in the autumn of 1839. He was made a Commander of the Order of the Bath (CB) in July 1838, and advanced to KCB in December 1839. He commanded the cavalry division of Sir Hugh Gough's army in the short campaign against the Marathas of Gwalior at the end of 1843, and was mentioned in Gough's despatch after the Battle of Maharajpur. In the First Anglo-Sikh War he was again in command of the cavalry at the Battle of Sobraon on 10 February 1846. He led the cavalry in file over the entrenchments