As a child, he developed a love of hunting and exploring, because he was raised in the wilderness. While he was a young man, Lewis fought against the Whiskey Rebellion in 1794. He became an officer in the army and battled against Native Americans in the Northwest Territory. Lewis soon learned a lot about Native Americans and their languages. In 1801, President Thomas Jefferson recruited Lewis to be his private secretary. When Jefferson had proposed such an expedition in 1792, Lewis had been among the first volunteers, although his youth and inexperience disqualified him at the time. When he became experienced in frontier, Lewis made a perfect candidate in Jefferson's eyes, and the President soon set out a course of study that would equip him with the scientific skills needed for his journey.
Lewis selected William Clark, a fellow Virginian with whom he had served on the frontier in 1795, to serve a co-leader. They set out by keelboat (see right) in 1803 to Wood River, Illinois, at the confluence of the Missouri and Mississippi rivers. The next spring, they began their journey up the Missouri River and by October had reached the Mandan villages in present-day North Dakota, where they decided to stay for the winter. Relying completely upon the goodwill of Indian peoples for their success, Lewis and Clark received food, military protection, and valuable information about the path ahead. Their most valuable help came in the form of Touissant Charbonneau, a French Canadian whom they hired as an interpreter, and his Shoshone wife Sacagawea, who provided help as a guide and interpreter. Sacagawea's very presence helped insure good relations with Indian people. In April 1805 all thirty-three members of the expedition left the Mandan village and started up the Missouri again. A band of Shoshone led by Sacagawea's brother provided invaluable assistance, primarily horses, as the expedition began to ascend the Rocky Mountains. After crossing the Bitterroot Mountains, they arrived cold, wet, hungry and exhausted, the Nez Percé village were they were taken in. In November, they traveled down the Columbia River basin and reached the Pacific Ocean in November. They stayed the winter on the Pacific Coast and returned to the United States in 1806.