James Kirker, "Indian fighter," is among the most infamous characters of the American West. In his exhaustively researched biography, Ralph Adam Smith explores the controversy surrounding the life of this frontier figure. Kirker emigrated from Ireland to New York City in 1810. In the years that followed, he was a privateer (in the War of 1812), a British captive, a merchant, a mountain man, the head of a private army, and a dominant figure in New Mexico politics.

When Apache and Comanche Indians from the United States began raiding frequently in northern Mexico, the Mexican government,...