<Li> September 23: The Corps arrives in St. Louis, ending their journey after two years, four months, and ten days . </Li> <P> For years, Jefferson had heard of and read accounts of the various ventures of other explorers in parts of the western frontier and consequently had a long - held interest in further exploring this largely still unknown region of the continent . In the 1780s, while Minister to France, Jefferson met John Ledyard in Paris and discussed a proposed trip to the Pacific Northwest . Jefferson had also read Captain James Cook's A Voyage to the Pacific Ocean (London, 1784), an account of Cook's third voyage, and Le Page du Pratz's The History of Louisiana (London, 1763), all of which greatly influenced his decision to send an expedition . Like Captain Cook, Jefferson also wished to discover a practical route through the Northwest to the Pacific coast . Alexander Mackenzie had already charted a route in his quest for the Pacific, first following the later - named Mackenzie River to the Arctic Ocean in 1789 . Mackenzie and his party then became the first on record to cross America north of Mexico to the Pacific, when he arrived near Bella Coola in 1793--a dozen years before Lewis and Clark . Mackenzie's accounts in Voyages from Montreal (1801) informed Jefferson (who read the book at Monticello in 1802) of Britain's intent to control the lucrative fur trade of the Columbia River, and convinced him of the importance of securing the territory as soon as possible . </P> <P> Two years into his presidency, Jefferson asked Congress to fund an expedition through the Louisiana territory to the Pacific Ocean . He did not attempt to hide the Lewis and Clark expedition itself from Spanish, French, and British officials, but rather claimed different reasons for the venture . He used a secret message to ask for funding due to poor relations with the opposition party in Congress . </P> <P> In 1803, Jefferson commissioned the Corps of Discovery, and named U.S. Army Captain Meriwether Lewis its leader, who in turn selected William Clark as second in command . Lewis demonstrated remarkable skills and potential as a frontiersman . As the expedition was gaining approval and funding, Jefferson made efforts to prepare him for the long journey ahead . Jefferson chose Lewis to lead the expedition rather than a "qualified scientist" because, "It was impossible to find a character who to a complete science in botany, natural history, mineralogy & astronomy, joined the firmness of constitution & character, prudence, habits adapted to the woods & a familiarity with the Indian manners and character, requisite for this undertaking . All the latter qualifications Capt . Lewis has ." </P>

Who led an expedition to explore the louisiana territory