In this enduring classic of American historiography, Frederick Merk challenges the triumphalist narratives surrounding Manifest Destiny and reconsiders the ideological foundations of American expansionism. Rather than portraying Manifest Destiny as an inevitable or universally accepted national impulse, Merk traces its evolution as a contested and often divisive doctrine—shaped by political agendas, religious ideals, and cultural anxieties. He deftly examines how expansionist fervor was not merely about land acquisition but entwined with a sense of divine mission and civilizational superiority. Drawing on an impressive range of primary sources, Merk explores the varying interpretations of Manifest Destiny from the 1840s through the Gilded Age, exposing the limits and contradictions of the ideology that helped fuel the Mexican War, the annexation of Oregon and Texas, and debates over imperialism. His work stands as both a critique of nationalist mythmaking and a call for sober historical inquiry. Manifest Destiny and Mission remains essential reading for anyone seeking to understand the moral and political complexities of American expansion.