The Fox wars.—By the end of the seventeenth century Fox hostilities had practically closed the Fox-Wisconsin trade route to the Mississippi. Hostility was increased by the massacre of many Fox Indians at Detroit in 1712. In 1715 De Lignery led a futile expedition against the tribe at Green Bay. In the following year Louvigny with eight hundred men won a partial victory at Butte des Morts, near Lake Winnebago. The European war had now closed, and the Lake Superior posts—Green
The new Sioux posts.—A new movement into the Sioux country was stimulated by the long standing desire to find a route to the Pacific. In 1723 Father Charlevoix suggested finding it either by means of a line of posts through the Sioux country or by way of the Missouri and over the mountains. The former plan was adopted, and in 1727 Fort Beauharnois was built on the west bank of Lake Pepin, with Perrière in command, and with new missions in the vicinity. But, through another uprising of the Fox Indians, the post was soon abandoned. New expeditions against the Foxes and the Sauks, their allies, broke their resistance, and after 1733 the Fox-Wisconsin trade route to the Iowa and Minnesota country was again open. After 1750 the Foxes were regular allies of the French in their wars with the British.
The Vérendrye and the Post of the Western Sea.—The search for the route to the Western Sea was taken up by Gaultier de Varennes (the elder La Vérendrye), commander at Fort Nepigon, who planned a fine of posts through the waterways northwest of Lake Superior. His movements were stimulated by the activities of the Hudson's Bay Company in Canada, and by those of the Spaniards in the Southwest. To pay the expenses of his scheme he was granted a monopoly of the northwestern fur trade. In the course of ten years he founded posts on Rainy Lake (St. Pierre, 1731), Lake of the Woods (St. Charles, 1731), Lake Winnipeg (Maurepas, 1732), Assiniboine River (La Reine), and on the Saskatchewan (Fort Dauphin, 1741). In 1742 La France had penetrated the Hudson's Bay Company territory by crossing from Lake Winnipeg to York Factory.
From this line of posts the elder La Vérendrye turned his attention to the upper Missouri, leading an expedition southwestward to the Mantannes in 1738. Four years later his son, Pierre de Varennes, made another expedition to the Mantannes, where they heard of bearded white men to the west. Setting out southwestward, they visited the Cheyennes, Crows, Little Foxes, and Bows. On January 1, 1743, when in the neighborhood of the North Platte River, they saw the Rocky Mountains.
After Vérendrye died, his successor, Legardeur St. Pierre, extended the line of posts up the Saskatchewan to the foot of the Rockies, where in 1752 he founded Fort La Jonquiere. The French had thus reached the Rockies by way of nearly every important stream between the Red River and the Saskatchewan.