Before the purchase was made Jefferson had planned an expedition to explore this region, and Congress had voted money to carry out his plan. Two officers of the United States army, Captain Meriwether Lewis and Captain William Clark, brother of George Rogers Clark, were put in command of the expedition. They were to ascend the Missouri River to its head and then find the nearest waterway to the Pacific coast. They were directed also to draw maps of the region and to report on the nature of the country and the people, plants, animals, and other matters of interest in the new lands. [Illustration: Meriwether Lewis.] In May, 1804, the little company of forty-five men left St. Louis and started up the Missouri River, passing the scattered settlements of French creoles. After eleven days they reached the home of Daniel Boone, the last settlement they passed on the Missouri. Leaving that, they found no more white settlers and very few Indians. But the woods were alive with game, so there was no lack of food. [Illustration: William Clark.] Late in October they arrived at a village of Mandan Indians situated at the great bend of the Missouri River, in what is now known as North Dakota. Deciding to winter here, they built huts and a stockade, calling the camp Fort Mandan. The Mandans were used to white men, as the village had been visited often by traders from both north and south. Although the Indians gave them no trouble, the explorers suffered greatly from cold and hunger, game being scarce and poor in the winter season. When spring came the party, now numbering thirty-two, again took up the westward journey. All before them was new country. They met few Indians and found themselves in one of the finest hunting-grounds in the world. Sage-fowl and prairie-fowl, ducks of all sorts, swans, and wild cranes were plentiful, while huge, flapping geese nested in the tops of the cottonwood-trees. [Illustration: Buffalo Hunted by Indians.] Big game, such as buffalo, elk, antelope, whitetail and blacktail deer, and big-horned sheep, was also abundant. It happened more than once that the party was detained for an hour or more while a great herd of buffalo ploughed their way down the bank of a river in a huge column. Many of the animals in this region were very tame, for they had not learned to fear men. Yet among them the explorers found some dangerous enemies. One was the grizzly bear, and another the rattlesnake. But the greatest scourges of all were the tiny, buzzing mosquitoes, which beset them in great swarms. The second autumn was almost upon them when they arrived at the headwaters of the Missouri, and their hardest task was yet to be accomplished. Before them rose the mountains. These, they knew, must be crossed before they could hope to find any waterway to the coast. The boats in which they had come thus far, now being useless, were left behind, and horses were procured from a band of wandering Indians.