This book offers a major rereading of US foreign policy from Thomas Jefferson’s purchase of Louisiana expanse to the Korean War. This period of one hundred and fifty years saw the expansion of the United States from fragile republic to transcontinental giant. David Mayers explores the dissenting voices which accompanied this dramatic ascent, focusing on dissenters within the political and military establishment and on the recurrent patterns of dissent that have transcended particular policies and crises. The most stubborn of these sprang from anxiety over the material and political costs of empire while other strands of dissent have been rooted in ideas of exigent justice, realpolitik, and moral duties existing beyond borders. Such dissent is evident again in the contemporary world when the US occupies the position of preeminent global power. Professor Mayers’s study reminds us that America’s path to power was not as straightforward as it might now seem.