The decades that followed independence from Spain in 1821 transformed Mexico from a strong, stable colony to a republic suffering from economic decline and political turmoil. This chaotic state hindered efforts of the young republic to meet the aggressive expansionism of the United States between 1845 and 1848.Santoni sheds new light on Mexican domestic history during the conflict—a much neglected subject—through a comprehensive examination of the only Mexican political bloc that wanted war with the United States. Led by Valentín Gómez Farías, this faction was the radical federalists, who in 1846 took the name of puros.Santoni demonstrates the reasons for the failure of the puros’ attempts to reestablish federalism in Mexico, shape public opinion, develop a civic militia and forge alliances with senior army officers and opposing political groups. Santoni maintains that the economic, social, and political troubles of Mexico ified the puros’ endeavors to direct armed resistance against the Americans.