Often hailed as the godfather of today's elite special forces, Robert Rogers trained and led an unorthodox unit of green provincials, raw woodsmen, farmers, and Indian scouts on "impossible" missions in colonial America that are still the stuff of soldiers' legend. The child of marginalized Scots-Irish immigrants, Rogers learned to survive in New England's dark and deadly forests, grasping, as did few others, that a new world required new forms of...