Carmichael-Smyth returned to India in 1810 as a captain, and served in the Invasion of Java in 1811. Thereafter he returned to Bengal and went to Callinger as a field engineer where he was mentioned in dispatches for exemplary valour in 1812. He subsequently was deployed on surveys before he was selected to assist in a campaign against Alwar. Following the campaign he returned to his position as garrison engineer at Agra where he would remain until 1819. During the Anglo-Nepalese War between 1814 and 1816 he served in all the operations under Sir David Ochterlony. In February 1817 he assisted in the reduction of Hathras. That same year he joined the army of Lord Hastings in the Third Anglo-Maratha War. On 13 March 1817 at Cawnpore he married Anne Thackeray, the widow of Richmond Thackeray, and became step-father to a young William Makepeace Thackeray. He returned to England in 1820 and was elevated to Major in 1821.