In his formal acceptance of the Republican presidential nomination in 1868, General Ulysses S. Grant concluded with four words that struck a deep chord with voters: “Let us have peace.” Historians have described the conflict in Vietnam as America's longest war. But, arguably, the nineteenth-century decades of sectional strife punctuated by a four-year conflict Americans call the Civil War truly represents the nation's longest war. It was certainly its most intense and violent war. In a country with less than one sixth of the population it contained a century later, the number of American soldier deaths in the Civil War was almost eleven times greater than those in Vietnam. And to this total of 625,000 Civil War dead, one must add hundreds more in the Kansas wars of the 1850s that anticipated the war of 1861–1865 and the thousands of deaths in Reconstruction battles that illustrated a sort of Clausewitzian corollary that politics were the continuation of war by similar means.

Grant's plea for peace in 1868 resonated with such meaning because the country had not known real peace since the outbreak of war with Mexico in 1846. During congressional debates over the issue of slavery in the territories acquired from Mexico, fistfights broke out on the floor of the House, Senator Jefferson Davis of Mississippi challenged an Illinois congressman to a duel, Senator Henry Foote (also of Mississippi) drew a loaded revolver on the Senate floor, and Congressman Alexander Stephens of Georgia declared that to resist “the dictation of the Northern hordes of Goths and Vandals” the slave states must make “the necessary preparations of men and money, arms and munitions, etc.