Every time Union armies invaded Southern territory there were unintended consequences. Military campaigns always affected the local population — devastating farms and towns, making refugees of the inhabitants, undermining slavery. Local conditions in turn altered the course of military events. The social effects of military campaigns resonated throughout geographic regions and across time. Campaigns and battles often had a serious impact on national politics and international affairs. Not all campaigns in the Civil War had a dramatic impact on the country, but every campaign, no matter how small, had dramatic and traumatic effects on local communities. Civil War military operations did not occur in a vacuum; there was a price to be paid on many levels of society in both North and South. The Oxford Handbook of the American Civil War assembles the contributions of thirty-nine leading scholars of the Civil War, each chapter advancing the central thesis that operational military history is decisively linked to the social and political history of Civil War America. The chapters cover all three major theaters of the war and include discussions of Bleeding Kansas, the Union naval blockade, the South West, American Indians, and Reconstruction. Each essay offers a particular interpretation of how one of the war’s campaigns resonated in the larger world of the North and South. Taken together, these chapters illuminate how key transformations operated across national, regional, and local spheres, covering key topics such as politics, race, slavery, emancipation, gender, loyalty, and guerrilla warfare.