Route to the Assiniboine River

The Route to 'Fort Chaboilez's on the Assinna Boin'

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Interactive historic map showing modern geographical names

Courtesy Missouri Historical Society

This map contains reminders and a sketch made by Lewis and Clark during their conversations with François Larocque and other traders from the North West Company's trading post, Fort Assiniboine, at the mouth of the Souris (Mouse) River. It is difficult to make sense of some of the details, partly because several figures refer to miles, and others to leagues (3.0 statute miles, or 4.8 kilometers).

The manager, or bourgeois, at Fort Assiniboine was Charles Chaboilez, to whom Lewis and Clark sent a cautiously cordial letter via free trader Hugh McCracken on October 31, 1804. They informed Chaboilez that they were sent by the U.S. government "for the purpose of exploring the river Missouri, and the western parts of the continent of North America, with a view to the promotion of general science." Lewis assured him of President Jefferson's open border, free trade policy:

We shall, at all times, extend our protection as well to British subjects as American citizens, who may visit the Indians of our neighbourhood, provided they are well-disposed; this we are disposed to do, as well from the pleasure we feel in becoming serviceable to good men, as from a conviction that it is consonant with the liberal policy of our government, not only to admit within her territory the free egress and regress of all citizens and subjects of foreign powers with which she is in amity, but also to extend to them her protection, while within limits of her jurisdiction.1

Chaboilez replied in due time, expressing "a great anxiety to Serve us," Clark noted, "in any thing in his power." The Canadian's letter was delivered on December 16, 1804 (in 6 days—express mail, considering the severity of winter on the High Plains) by Hugh Heney, or Hené. We don't know what the factor wrote, but we do know that the courier-trader made a hit with the captains, who, according to Larocque, "Enquired a great deal of Mr. Heney, Concerning the sioux Nation, & Local Circumstances of that Country & lower part of the Missouri, of which they took notes."2 In fact, the illustration above may be the record of that conversation.

Lewis and Clark's "Miry Creek" was a translation of Bourbeuse—"Miry"—by which Larocque knew it. In June of 1805 Larocque recorded his own experience in fording it: "We unloaded our horses and crossed the property on our shoulders there being not more than 2 feet [of] water, but we sunk up to our middle in mud, the horses bemired themselves in crossing and it was with difficulty we got them over the banks being bogs as also the bed of the river."3 Later called Snake Creek, its lower 17 miles became part of Lake Sakakawea when Garrison Dam was completed in 1956.

Turtle Mountain, with its summit only 500 feet above the surrounding plain, is nonetheless the most conspicuous landmark in the vicinity. It is the centerpiece of the 3,118-acre (1,257 hectare) International Peace Garden, which straddles the 49th parallel, two thirds of it in Manitoba, the rest in North Dakota. It is not a mountain in the "Rocky" sense, but a heavily wooded mass of glacial drift. The area is dotted with many small lakes.4

1. Donald Jackson, ed., Letters of the Lewis and Clark Expedition with Related Documents,1783–1854 (2 vols., Urbana: University of Illinois Press, 2nd ed., 1978), 1:213–14. The phrase "serviceable to good men" may suggest that Lewis was consciously practicing the precepts of Freemasonry, an affiliation that is evidenced a number of times in his expedition journals. Back in Virginia, Lewis had risen quickly from Fellowcraft to Past Master Mason within the first four months of 1797. By October, 1799, he was a Royal Arch Mason, which represented the completion of the Master Mason's degree.

2. W. Raymond Wood and Thomas D. Thiessen, Early Fur Trade on the Northern Plains: Canadian Traders Among the Mandan and Hidatsa Indians, 1738–1818 (Norman: University of Oklahoma Press, 1985), 143.

3. Ibid., p. 164.

4. See Elliott Coues, New Light on the Early History of the Greater Northwest (reprint, 1956, 3 vols.; New York: Harper, 1897), 1:308n.