In 1804-06, Captains Meriwether Lewis and William Clark led about 40 soldiers and boatmen on an epic journey after President Thomas Jefferson commissioned the Corps of Discovery to find a route to the Pacific Ocean through the newly acquired Louisiana territory. Along the way, they mapped the land, recorded its resources, and contacted its native inhabitants. The United States had purchased the Louisiana territory, more than 830,000 square miles, from France in 1803. Jefferson selected Meriwether Lewis to lead the expedition, and with Jefferson's permission Lewis asked his friend and former commanding officer, William Clark, to serve as co-leader. Although opposite in temperament, Lewis and Clark worked harmoniously throughout the two-year journey.