Meriwether Lewis (1774-1809) was born in Albemarle County, Virginia —the same county in which Thomas Jefferson was born in 1743. Lewis appeared destined for the life of a Virginia gentleman farmer, but in 1794, when Pennsylvania insurgents (people revolting against an authority) brought on the Whiskey Rebellion, Lewis answered President George Washington's call for militia volunteers. The campaign was bloodless, but Lewis enjoyed himself. He wrote his mother, "I am quite delighted with a soldier's life."

While on frontier duty, Lewis met William Clark (1770-1838), who was commanding the special company of sharpshooters to which Lewis was transferred. After service on the Mississippi River, Lewis was asked by his old Virginia friend Thomas Jefferson, now president of the United States, to become his confidential White House secretary. While Lewis served in that capacity from 1801 until 1803, the president discussed with him his dream of...