In the early spring of 1835, John Marshall Clemens and his wife, Jane, loaded up their possessions, their five children, and their single slave, in Three Forks, Tennessee, to move to Missouri. It was another in a long series of migrations which the family undertook, seeking the success and affluence which always eluded them. As Dixon Wecter has noted, the Clemenses "appeared to lack the golden touch, even in an age when the riches of inland America hung ripe for the plucking." Their destination, Florida, Missouri, was an unpromising village with two muddy streets, a hundred inhabitants, and the Salt River, which farfetched optimists predicted would be navigable in the near future; but their family's journey this time would produce a legacy more impressive than all their schemes for wealth and status combined. Along the way, John Marshall and Jane Lampton Clemens conceived their sixth child. At his birth...