In 1804-06, Captains Meriwether Lewis and William Clark led about 40 soldiers and boatmen on a journey commissioned by President Thomas Jefferson to find a route to the Pacific Ocean through the newly acquired Louisiana territory. This Corps of Discovery mapped the land, recorded its resources, and contacted its native inhabitants. The United States had purchased the Louisiana territory, more than 870,000 square miles, from France in 1803, and Jefferson chose Lewis to lead the expedition; with Jefferson's permission, Lewis asked his friend and former commanding officer William Clark to serve as co-leader, and although they were opposite in temperament, they worked harmoniously throughout the two-year journey.