Born in Quebec, Canada, February, 1667; killed, 1707. Entering the Séminaire des Missions Etrangeres of Quebec, he was ordained in 1690 and after serving for a time at Minas, Nova Scotia (then Acadia), was assigned to the western mission. He laboured for a time at the Cahokia (Tamaroa) mission in Illinois, until succeeded by Father Jean Bergier, probably about 1698, after which he followed Fathers Montigny and Davion, of the same seminary, to the lower Mississippi, and took up his residence among the Natchez, about the present Natchez, Mississippi, establishing the first mission in the tribe, apparently about the end of 1699. The tribes of this region, however, were generally obdurate and neither secular missionaries nor Jesuits met with success, so that by the end of 1704 all but the Natchez mission had been abandoned, leaving Father St-Cosme alone. After several years of unrequited labour, he was finally murdered, with three French companions and a slave, while descending the Mississippi, being attacked while asleep by a party of the savage Shetimasha. To avenge this death, Bienville, Governor of Louisiana, summoned the Natchez and other friendly tribes to take up arms against the Shetimasha, with the result that the latter tribe was almost exterminated. A cousin of the same name was also a priest in Quebec (b. 1660; d. 1712).
SHEA, Catholic Missions (New York, 1854); Jesuit Relations, ed. THWAITES, LXV, note (Cleveland. 1896-1901); LA HAYE, Journal historique (New Orleans, 1831).