In 1803, President Jefferson agreed with Napoleon Bonaparte on the Louisiana Purchase by which the United States would expand its territory westward. After the US received the land by means of the purchase, Jefferson appointed Captain Lewis and Second Lieutenant Clarck to lead an expedition to the west. The expedition would provide valuable information about this new territory (the area's plants, animal life, and geography) which would be very helpful for the settlers to survive there. Besides, Jefferson aimed to declare US sovereignty over the land which was occupied by many different Indian tribes.