Marie Joseph François (Francis) Garnier (25 July 1839 - 21 December 1873) was a French officer and explorer known for his exploration of the Mekong River in Southeast Asia.
He was born at St. Etienne. He entered the French Navy, and after voyaging in Brazilian waters and the Pacific he obtained a post on the staff of Admiral Charner, who from 1860 to 1862 was campaigning in Cochin China.
After some time spent in France he returned to the East, and in 1862 he was appointed inspector of the natives in Cochin China, and entrusted with the administration of Cho-lon, a suburb of Saigon. It was at his suggestion that the marquis de Chasseloup-Laubat determined to send a mission to explore the valley of the Mekong River, but as Garnier was not considered old enough to be put in command, the chief authority was entrusted to Captain Ernest Doudard de Lagrée. In the course of the expedition - to quote the words of Sir Roderick Murchison addressed to the youthful traveller when, in 1870, he was presented with the Victoria Medal of the Royal Geographical Society of London - "from Kratie in Cambodia to Shanghai 5392 mi were traversed, and of these 3625 mi, chiefly of country unknown to European geography, were surveyed with care, and the positions fixed by astronomical observations, nearly the whole of the observations being taken by Garnier himself".
Volunteering to lead a detachment to Talifu, the capital of Sultan Suleiman, the sovereign of the Muslim rebels in Yunnan, he successfully carried out the more-than-adventurous enterprise. When shortly afterwards Lagree died, Garnier naturally assumed the command of the expedition, and he conducted it in safety to the Yang-tsze-Kiang, and thus to the Chinese coast. On his return to France he was received with enthusiasm. The preparation of his narrative was interrupted by the Franco-Prussian War, and during the siege of Paris he served as principal staff officer to the admiral in command of the eighth sector. His experiences during the siege were published anonymously in the feuilleton of Le Temps, and appeared separately as Le Siege de Paris, journal d'un officier de marine (1871).
Returning to Cochin China he found the political circumstances of the country unfavourable to further exploration, and accordingly he went to China, and in 1873 followed the upper course of the Yang-tsze-Kiang to the waterfalls. He was next commissioned by Admiral Dupre, governor of Cochin China, to found a French protectorate or a new colony in Tonkin. On 20 November 1873 he took Hanoi, the capital of Tonkin, but a month later he was slain in a fight with the Black Flags.
Garnier's chief fame rests on the fact that he originated the idea of exploring the Mekong, and carried out the larger portion of the work.
In 1943, French Indochina issued a postage stamp honoring Garnier.