Chesney, Francis Rawdon (1789–1872), soldier and explorer, was born 16 March 1789 at Ballyveagh, near Annalong, Co. Down, eldest son of Capt. Alexander Chesney, coastguard officer, of Ballymena, Co. Antrim, and his second wife, Jane (née Wilson), of Ballymena. Capt. Chesney had been a loyalist in South Carolina during the American revolution, and had returned to Ireland at the end of the war; he named his son in honour of his old commander in America, Francis Rawdon-Hastings (qv), earl of Moira. At the age of nine Francis was appointed sub-lieutenant in a yeomanry corps raised by his father, and during the 1798 insurrection he walked the twenty miles (32 km) barefoot from Kilkeel to Newry to join his unit. Although he served during the insurrection, he does not appear to have seen any action, as south Down was relatively peaceful. In 1803 Moira presented him with a cadetship at the Royal Artillery academy at Woolwich, and he was commissioned in the Royal Artillery in 1805. He performed routine garrison duties until 1829, when he volunteered to observe the Russo–Turkish war and to assist the Turks in forming a rocket corps, but he arrived in Constantinople after the war had ended. He took the opportunity to make an exploratory tour of Egypt and Syria, surveying the Red Sea and Euphrates routes to India. His report contradicted previous French estimates and concluded that the construction of a sea-level canal at Suez was feasible; his findings were crucial in persuading Ferdinand de Lesseps to undertake the project.
Chesney was a brave and energetic officer, whose diminutive stature disguised great physical toughness. He surveyed the lower Euphrates by raft, and returned to England in September 1832 convinced that the river was navigable and that it provided a rapid route to India; establishing a British presence in Mesopotamia would also, he believed, discourage Russian encroachment. In April 1833 Chesney had a well publicised interview with William IV, who became a strong supporter of the Euphrates scheme. Chesney's lobbying led to the appointment of a select committee which in June 1834 voted £20,000 for an exploratory expedition. Chesney was appointed to lead its fourteen officers and thirty-nine men, and given the temporary rank of colonel; his second in command was Henry Blosse Lynch (qv), a Mayo-born officer in the Indian navy.
On 10 February 1835 they sailed for Syria. The expedition faced immense difficulties: the steamships, Euphrates and Tigris, had to be hauled in sections over fifty miles of difficult terrain from Antioch to Bir on the Euphrates; the Arab tribes along the route were hostile; and many of the men, including Chesney, suffered seriously from malaria. On 21 May 1836 the Tigris was wrecked in a sudden storm with the loss of twenty lives. Chesney ignored orders from London to abandon the expedition, and the Euphrates eventually reached Basra in the Persian Gulf on 19 June 1836, proving that steamships could navigate the river. He then explored the Tigris and the Karun delta, and travelled on to Bombay, where he was fêted. He returned to England in August 1837 and was awarded the Geographical Society's gold medal. However, he received a cool reception from the government: although his persistence and courage had been crucial to the completion of the expedition, his actions had often been impetuous and his judgement faulty.
After four years spent preparing an account of the expedition, he returned to regimental duty in 1841, and commanded the artillery at Hong Kong (1843–7). On his return to England he published the first two volumes, geographical and historical, of the Expedition for the survey of the rivers Euphrates and Tigris (1850) (3rd vol., Narrative of the Euphrates expedition (1868)); he also published a History of . . . firearms (1852) and the Russo–Turkish campaigns of 1828–9 (1854). His last military appointment was as colonel commandant of the Cork district (1847–52), after which he retired to his home at Pakolet, near Kilkeel, Co. Down. In 1856 he participated in another expedition to survey the construction of a railway through the Euphrates valley. In 1857 and 1863 he visited Constantinople to seek the required concessions from the Turkish government, and also visited Syria (accompanied by Sir John Benjamin Macneill (qv)), to survey its suitability for a rail link, but he returned to England to find that Palmerston would not proceed because of objections from the French. He received an honorary DCL from Oxford (1850), was elected fellow of the Royal Society and of the Royal Geographical Society, and was promoted major-general (1855) and full general (1868). When he visited Paris in 1869 de Lesseps dubbed him ‘father of the Suez canal’. He remained strong and fit into his eighties, when he regularly walked the Mourne mountains. In 1871 he gave evidence to a commons committee examining the Euphrates railway project, but before its favourable (if ineffectual) report was issued he died at Pakolet 30 January 1872. A portrait of Chesney dated 1853, possibly by the German artist Carl Schmid, is held in the Ulster Museum.
He married first (1822) Georgette Forster, who died in 1825 leaving one daughter; secondly (1839) Everilda Fraser (d. 1840); and thirdly (1848) Louisa Fletcher, with whom he had four sons and a daughter.