The sitter was the sixth child and eldest son of the 1st Earl Cornwallis. In 1776 he sailed for America, in command of seven regiments of infantry, to reinforce the English Army there. He displayed considerable military ability and achieved many notable successes during the American war of Independence, before finally being defeated and forced to surrender at Yorktown on 19 October 1781.
Despite the loss of the war against America, William Pitt believed Cornwallis to be 'the only man capable of restoring the military and civil services of India to an efficient state, and of repairing the bad effect upon English prestige of the defeats experienced in the second Mysore War.' On 23 February 1786 Cornwallis accepted the post of governor-general and commander-in-chief in India, where he began with reforming the civil and military posts of the East India Company. The outbreak of the third Mysore war in 1790 resulted in Cornwallis leaving Bengal to take control of the troops stationed in Madras. He besieged Tipu Sultan's fort at Seringapatam and forced him to sign a punitive peace treaty, which broke his power and destroyed the prestige of the ruling Mysore dynasty. He was created Marquis Cornwallis in 1792 in recognition of his services in India. He left India for England on 10 October 1793.
By 1798 the state of affairs in Ireland had deteriorated to such a level that Cornwallis was asked to accept the two offices of viceroy and commander-in-chief. His viceroyalty was marked by the suppression of the rebellion of 1798 and by the passing of the Act of Union. He resigned his posts in 1801 on the refusal of the King George III to contemplate Catholic emancipation. A respected statesman, he was subsequently sent to France to negotiate the treaty of Amiens with the French plenipotentiary Joseph Bonaparte.
Despite his wish to retire, he reluctantly accepted the demand for him to return to India in 1805 at the age of sixty-six, to negotiate peace with both Scindia and Holkar. However his health failed while he was travelling up the Ganges and he died at Ghazipur on 5 October 1805. He was highly honoured both in India and England; the Indian government erected a mausoleum at Ghazipur and statues were built in Madras, Bombay and in St. Paul's Cathedral, London.
Another portrait of the 1st Marquis Cornwallis, full-length, by Daniel Gardner was previously with Thomas Agnew's and Sons and a portrait of him by Thomas Gainsborough, R.A. is in the National Portrait Gallery, London.