The term "Manifest Destiny" has traditionally been linked to U.S. westward expansion in the nineteenth century, the desire to spread republican government, and racialist theories like Anglo-Saxonism. Yet few people realize the degree to which "Manifest Destiny" and American republicanism relied on a deeply anti-Catholic civil-religious discourse. John C. Pinheiro traces the rise to prominence of this discourse, beginning in the 1820s and culminating in the Mexican-American War of 1846-1848. Pinheiro begins with social reformer and Protestant evangelist Lyman Beecher, who was largely responsible for synthesizing seemingly unrelated strands of religious, patriotic, expansionist, and political sentiment into one universally understood argument about the future of the United States. When the overwhelmingly Protestant United States went to war with Catholic Mexico, this "Beecherite Synthesis" provided Americans with the most important means of defining their own identity, understanding Mexicans, and interpreting the larger meaning of the war. Anti-Catholic rhetoric constituted an integral piece of nearly every major argument for or against the war and was so universally accepted that recruiters, politicians, diplomats, journalists, soldiers, evangelical activists, abolitionists, and pacifists used it. It was also, Pinheiro shows, the primary tool used by American soldiers to interpret Mexico's culture. All this activity in turn reshaped the anti-Catholic movement. Preachers could now use caricatures of Mexicans to illustrate Roman Catholic depravity and nativists could point to Mexico as a warning about what America would be like if dominated by Catholics. Missionaries of Republicanism provides a critical new perspective on ''Manifest Destiny,'' American republicanism, anti-Catholicism, and Mexican-American relations in the nineteenth century.

This is not another chronological retelling of the Mexican War. Instead, it examines civil-military clashes during the war in light of Jacksonian politics and the American citizen-soldier tradition, looking at events that shed light on civilian authority over the military, as well as the far reaching impact of political ambition during this period (specifically, presidential power and the quest for the presidency). By 1848, Americans had come to realize that in their burgeoning democracy, generals and politicians could scarcely resist the temptation to use war for partisan gain. It was a lesson well learned and one that still resonates today. The Mexican War is known for the invaluable experience it provided to future Civil War officers and as an example of America's drive to fulfill her Manifest Destiny. Yet it was more than a training ground, more than a display of imperialism. Significantly, the Mexican War tested civilian control of the military and challenged traditional assumptions about the role of the army in American society. In so doing, it revealed the degree to which, by 1846, the harsh partisanships of the Jacksonian Era had impacted the American approach to war. This is not another chronological retelling of the Mexican War. Instead, it examines civil-military clashes during the war in light of Jacksonian politics and the American citizen-soldier tradition, looking both at events that shed light on civilian authority over the military and at the far reaching impact of political ambition during this period (specifically, presidential power and the quest for the presidency). In addition to politics, a host of others factors marred civil-military relations during the war, threatening U.S. victory. These included atrocities committed by Americans against Mexicans, disobedient officers, and inefficient U.S. military governors. In the end, as Manifest Ambition shows, Polk's ability to overcome his partisan leanings, his micro-management of the war effort, and his overall strategic vision, helped avoid both a prolonged occupation and the annexation of All Mexico. By 1848, Americans had come to realize that in their burgeoning democracy, generals and politicians could scarcely resist the temptation to use war for partisan gain. It was a lesson well learned and one that still resonates today.