Gregorio Cortez Lira, a ranchhand of Mexican parentage, was virtually unknown until one summer day in 1901 when he and a Texas sheriff, pistols in hand, blazed away at each other after a misunderstanding. The sheriff was killed and Gregorio fled immediately, realizing that in practice there was one law for Anglo-Texans, another for Texas-Mexicans. The chase, capture, and imprisonment of Cortez are high drama that cannot easily be forgotten. Even...