A provocative new biography of the man who forged America's alliance with the IroquoisWilliam Johnson was scarcely more than a boy when he left Ireland and his Gaelic, Catholic family to become a Protestant in the service of Britain's North American empire. In New York by 1738, Johnson moved to the frontiers along the Mohawk River, where he established himself as a fur trader and eventually became a landowner with vast estates; served as principal...