The Fort on the Missouri near the Knife River Replica, near Washburn, North Dakota
The captains ordered work to begin on the Corps of Discovery's winter fortification on the second of November, 1804; they completed it on the 27th. The mens' quarters, the storage rooms, and the 16-foot pickets front and back, were designed for defense against hostile Indians, especially the Sioux, who were quite troublesome that winter, although they never attacked the fort. "This place we have named Fort Mandan," Lewis recorded, "in honour of our Neighbours" – their kind and congenial Mandan Indians. Here they celebrated their second Christmas and New Year's.
On 28 February 1805, sixteen men were assigned to hew six canoes from cottonwood logs, finishing them in 22 days. Meanwhile, the rest of the men made rope, made leather clothing and mocassins, cured meat, made battle axes to trade for corn, and prepared botanical, zoological, and mineralogical for shipping back to Jefferson. Clark worked on a new map.
"All the party in high Spirits," Clark wrote approvingly, "but fiew nights pass without a Dance they are helth. except the – vn. [venereal]--which is common with the Indians and have been communicated to many of our party at this place – those favores bieng easy acquired. all Tranquile."
At 4 p.m. on the seventh of April the Corps of Discovery headed their six canoes and two pirogues up the Missouri toward the Rocky Mountain barrier. At the same moment Corporal Warfington and a small crew, accompanied by some Indians heading for a meeting with the President, headed downriver.
Mr. Jefferson had outlined their mission through the Northwest in a set of orders containing more than a hundred separate directives to look, listen, taste, smell and touch; to count, measure, weigh and describe; to map the land and meet the people who lived on it. Here, in the most carefully, sturdily constructed of their three winter encampments, they prepared reports on all they had observed and done so far, and arranged botanical, biological and mineralogical specimens for shipment back east. They quizzed their neighbors about the land that lay westward, and visited with Canadian traders from Fort Assiniboine, 150 miles to the north. They drew the first draft of the new map of the Northwest that ultimately, following its careful post-expeditionary revision, and publication at last in 1814, would be for the next 40 years the most complete and accurate chart of the Northwest.
Here they wintered-over near the Mandans, "the most friendly, well disposed Indians inhabiting the Missouri. . . . brave, humane and hospitable." They talked peace and commerce, American style, to all who would listen. On 7 April 1805, rested and refreshed, and tested by the rigors of a winter on the Northern Plains, they embarked again, "to penetrate a country at least two thousand miles in width on which the foot of civilized man had never trodden." Lewis proudly attested that his men were "in excellent health and sperits, zealously attached to the enterprise, and anxious to proceed; not a whisper of murmur or discontent to be heard among them," – in those days the noun murmur commonly meant "a grumbling, private complaint" – "but all act in unison, and with the most perfect harmony."
In short, it all came together at Fort Mandan. Even the travel schedule. "You may . . . expect me to meet you at Montachello in September 1806." He almost made it.
February on the Missouri near Fort Mandan Replica
Although the "Little Ice Age" was steadily warming, winters in the northern latitudes still averaged several degrees colder in 1805 than they do now. Today the Missouri River infrequently freezes over solid anywhere, even in northwestern North Dakota. The winds are just as strong, however, sculpting graceful shapes of driven snow among the rumpled edges of an ice jam.
Clark, who accompanied the hunters on a nine-day, 30-mile round trip in early February, explained what it was like to travel on the frozen river. The second day out he broke through the ice and got his feet and legs wet – a very dangerous situation. The third day out, he complained, "walking on uneaven ice has blistered the bottom of my feat, and walking is painfull to me--"
Moreover, conditions on the river changed every few days.