The so called "Cart War" erupted in 1857 and had national and international repercussions. The underlying causes of the event, historians believe, were ethnic and racial hostilities of Texans toward Mexican Texans, exacerbated by the ethnocentrism of the Know-Nothing party and the White anger over Mexican sympathy with Black slaves. By the mid-1850s, Mexicans and Tejanos had built a successful business of hauling food and merchandise from the port of Indianola to San Antonio and other towns in the interior of Texas. Using oxcarts, Mexicans moved freight more rapidly and cheaply than their Anglo competitors. Some Anglos retaliated by destroying the Mexicans' oxcarts, stealing their freight, and reportedly killing and wounding a number of Mexican carters. An attack on Mexican carters occurred in 1855 near Seguin, but sustained violence did not begin until July 1857. Local authorities made no serious effort to apprehend the criminals, and violence increased so much that some feared that a "campaign of death" against Mexicans was under way.
Public opinion in some counties between San Antonio and the coast ran heavily against the carters, who were regarded as an "intolerable nuisance." Some newspapers, however, spoke out against the violence. The Austin Southern Intelligencer and the San Antonio Herald expressed concern that the "war" would raise prices. The Intelligencer also worried that if attacks on a "weak race" were permitted, the next victims would be the German Texans, and that finally "a war between the poor and the rich" might occur. Some humanitarians also expressed concern for the Mexicans, notwithstanding "the fact of their being low in the scale of intelligence," as the Nueces Valley Weekly of Corpus Christi stated.
News of the violence in Texas soon reached the Mexican minister in Washington, Manuel Robles y Pezuela, who on October 14 protested the affair to Secretary of State Lewis Cass. Cass urged Texas governor Elisha M. Pease to end the hostilities. In a message to the state legislature of November 30, 1857, Pease declared: "It is now very evident that there is no security for the lives of citizens of Mexican origin engaged in the business of transportation, along the road from San Antonio to the Gulf." Pease asked for a special appropriation for the militia, and the legislators approved the expenditure with little opposition. Though some citizens of Karnes County, who wanted the "peon Mexican teamsters" out of business, were angry at the arrival of armed escorts for Tejano carters, the "war" subsided in December of 1857.