From 1804 to 1806, Captains Meriwether Lewis and William Clark led the Corps of Discovery on a journey to find a water route to the Pacific Ocean through the newly acquired Louisiana territory. Charged by President Thomas Jefferson, they mapped the land, recorded its resources, and met with and learned from its native inhabitants. In preparation, Meriwether Lewis studied medicine, botany, zoology, and celestial observation, and with Jefferson's permission asked his friend and former commanding officer, William Clark, to serve as co-leader. Clark contributed his skills as an outdoorsman, geographer, and map-maker, and despite their opposite temperaments, the two worked harmoniously throughout the two-year journey.