William Clark (1770-1838) was an explorer and statesman from Virginia. He formed part of the famous Lewis and Clark expedition to the West in 1803, with Meriwether Lewis, among others. Although during the expedition, Clark was technically a Lieutenant, he and Lewis were treated as co-captains in every respect. After the expedition, he was appointed by President Thomas Jefferson as principal Indian agent of the Louisiana Territory, during which time he negotiated intertribal peace treaties and convinced tribes that were potentially harmful to interests of the United States (such as the Sioux) to remain neutral or side against the British in the War of 1812. In 1813 he became the governor of Missouri Territory. When Missouri became a state in 1821, he lost his gubernatorial election bid, at which time he went back into Indian agency in St. Louis until shortly before his death in 1838.