La Salle, Ren Robert Cavelier, Sieur de (1643–1687), a French explorer of North America. Few of La Salle's ambitious ventures succeeded, yet his courage and vision won a vast empire for France in the New World. With great energy and determination he explored vast areas of what is now the United States and established a number of forts and settlements for France. He drove his men as hard as he drove himself. In the end, tired and mutinous followers murdered him.

La Salle was born on November 21, 1643, in Rouen, the son of a rich merchant. While in his early 20's he sailed to Canada and established a seigneury (a lord's estate) at Lachine, near Montreal. In 1669 he sailed up the St. Lawrence River to Lake Ontario. He became a friend of Count Louis de Frontenac, governor of New France, and in 1673 the count appointed La Salle commandant of Fort Frontenac, on the site of present Kingston, Ontario. Here La Salle developed a profitable fur trade.

In 1677 La Salle went to France. He convinced Louis XIV that the fur trade could be extended by more exploration and by building forts to hold the new territories. La Salle was given a title of nobility and returned to Canada with Henri de Tonti, who became his principal aide.

In 1679 Tonti built the Griffon, the first sailing vessel on the Great Lakes, and La Salle and his party sailed on it from the Niagara River to Green Bay, an arm of Lake Michigan in Wisconsin.

Leaving the Griffon, which disappeared on its return voyage, La Salle led his men in canoes along the western and southern shores of Lake Michigan to the present site of St. Joseph, Michigan, where they built Fort Miami. Going west to the Illinois River they erected Fort Crvecoeur (near Peoria) in 1680. La Salle sent Father Louis Hennepin to explore the upper Mississippi and returned—on foot in the middle of winter—to Fort Frontenac for supplies. Then, with Tonti, La Salle led a small party to the mouth of the Mississippi. Here, on April 9, 1682, he planted a cross, claiming the entire valley for France. In honor of Louis XIV he named it Louisiana.

In 1682–83 La Salle built Fort St. Louis at Starved Rock, Illinois. Relieved of his command by a new governor, he sailed to France in 1683 and got royal permission to govern all land between Lake Michigan and the Gulf of Mexico. With four ships La Salle sailed from France for the mouth of the Mississippi in 1684. He fell ill in the West Indies, and many of his followers deserted.

In 1685, failing to find the channel to the Mississippi's mouth, La Salle landed at Matagorda Bay, Texas. In January, 1687, he led a handful of men on a march to join Tonti in Illinois. His men grew mutinous, and on March 19, on the Brazos River in eastern Texas, three of them ambushed and killed him. Later, French settlers built the forts that La Salle had planned as a means of holding Louisiana for France.