The Constant Recurrence of Such Atrocities: Guerrilla Warfare and Counterinsurgency during the Mexican-American War

When guerrilla war first broke out in northern Mexico, the motives and modalities of the violence Americans and Mexicans inflicted on each other were informed by previous fighting with Native Americans, and American attitudes were also shaped by Jacksonian Democracy, with its hardening racial attitudes and vigilantism. In northern Mexico, US officers tried and failed to control atrocities against Mexican civilians. During the later US invasion of central Mexico, US officers sought to prevent guerrilla warfare by restraining US troops and threatening Mexican civilians with reprisals. After guerrilla warfare developed there and began to hamper their operations, commanders implicitly encouraged atrocities through their lack of action against US soldiers who committed them and the assignment of known perpetrators to counterinsurgency duty. US leaders did not use explicit legal reasoning and did not even always document de facto policies. During the Civil War, in contrast, US officers and lawyers developed anti-guerrilla policies that they documented in orders and justified through legal reasoning.