Pierre le Moyne Iberville, sieur d' (pyĕr lə mwän syör dēbĕrvēl´), 1661–1706, French Canadian naval officer, founder of the French territory of Louisiana, b. Ville Marie (in present Montreal), Canada; son of Charles le Moyne, sieur de Longueuil, and brother of Jean Baptiste le Moyne, sieur de Bienville. In 1675 he entered the French navy but after 10 years at sea returned to Canada. He led five expeditions (1686, 1689, 1691, 1694, 1697) against the British fur-trading posts on Hudson Bay. Despite these efforts, the British foothold was not broken, largely because Iberville received no support from France. In 1690 he took part in the raid on Schenectady led by his elder brother Jacques, sieur de Ste-Hélène. In 1692 he unsuccessfully attacked Fort Pemaquid, Maine, but in 1696 he destroyed that post and also captured St. John's, Newfoundland, temporarily ousting the British from that area. In 1698, Iberville, who was in France, was charged with planting a settlement in the lower Mississippi valley. With colonists and supplies in four ships, Iberville, accompanied by his younger brother Bienville, reached the Gulf of Mexico in 1699 and founded Old Biloxi (now Ocean Springs, Miss.). He was the first definitely to ascertain the mouth of the Mississippi from the Gulf approach and to explore its delta. He returned to the colony with supplies and reinforcements in 1700 and 1701–2. Illness prevented Iberville from returning again to the colony, which, under Bienville's direction, was moved to the Mobile area in 1702. Iberville recovered sufficiently to lead an expedition that captured (1706) the British islands of Nevis and St. Kitts in the West Indies and was ready to carry out an old plan to attack Boston and New York when, having put in at Havana, he was stricken with yellow fever and died.

See biography by N. M. Crouse (1954).