Lewis had served as Thomas Jefferson’s secretary.
In 1801, Lewis left the army and accepted an invitation to serve as Thomas Jefferson’s presidential secretary. Lewis had known Jefferson since he was a boy—he’d grown up on a Virginia plantation only a few miles from Monticello—and the pair went on to forge a mentor-protégé relationship while working together in the White House. When Jefferson conceived of his grand expedition to the West in 1802, he immediately named the rugged, intellectually gifted Lewis as its commander. To help the young secretary prepare, Jefferson gave him a crash course in the natural sciences and sent him to Philadelphia to study medicine, botany and celestial navigation.
