Background.

The 1910s were a tumultuous decade in Mexican politics, and U.S.-Mexican relations were strained to the limit. Born in poverty, Porfirio Diaz, who ruled Mexico from 1876 to 1911, had worked against French efforts to dominate Mexico in the nineteenth century. For most of his tenure in office he had kept democratic mechanisms in place, but by 1910 he was turning increasingly to coercion. Troops under Diaz's control suppressed strikes by textile workers and miners with bloody violence, and as many Mexican organizations began to oppose him, his regime was beginning to totter. Francisco I. Madero, a member of one of Mexico's ten richest families, ran against Diaz for the Mexican presidency in 1910, lost because of corrupt voting practices, and was imprisoned. Escaping to the United States, Madero rallied his forces, attacked Diaz's ill-disciplined federal troops, and on 25 May...