THE DAWN OF GUERILLA WARFARE Why the Tactics of Insurgents against Napoleon Failed in the US Mexican War

Swenson offers a concise yet far-reaching transnational analysis of the Mexican–American War, situating it within the broader evolution of modern irregular warfare. It traces the origins of nineteenth-century counterinsurgency to the Peninsular War (1808–1814), when Spanish guerrilla resistance fatally undermined Napoleon’s occupation and inspired new doctrines on unconventional warfare. Drawing on these precedents, Winfield Scott and Henry Halleck developed an innovative counterinsurgency and occupation policy during the U.S. campaign in Mexico (1846–1848), seeking to stabilise conquered regions through conciliation rather than coercion.
Swenson examines how lessons from Napoleonic Spain shaped U.S. strategy in 1847, influenced Mexican and American perceptions of the conflict, and informed varied forms of resistance to U.S. occupation. He also highlights the wider Atlantic context, including European monarchist interests in Mexico and the cautionary example of French overreach in Spain. The result is a historiographically significant study that reframes the Mexican–American War as a key moment in the global development of guerrilla warfare and military occupation policy.