The American Civil War (1861–1865) was a civil war between the United States of America, called the Union, and the Confederate States of America, formed by eleven Southern states that had declared their secession from the Union. more...
The Union won a decisive victory, followed by a period of Reconstruction. The war produced more than 970,000 casualties (3 percent of population), including approximately 560,000 deaths. The causes of the war, the reasons for the outcome, and even the name of the war itself, are subjects of much controversy, even today.
Historiography: Multiple explanations of why the War began
The origins of the American Civil War lay in the complex issues of slavery, politics, disagreements over the scope of States' rights versus federal power, expansionism, sectionalism, economics, modernization, and competing nationalism of the Antebellum period. Although there is little disagreement among historians on the details of the events that led to war, there is disagreement on exactly what caused what and the relative importance. There is no consensus on whether the war could have been avoided, or if it should have been avoided.
Failure to compromise
In 1854, the old Second Party System broke down after passage of the Kansas-Nebraska Act. The Whig Party disappeared, and the new Republican Party arose in its place. It was the nation's first major political party with only sectional appeal; though it had much of the old Whig economic platform, its popularity rested on its commitment to stop the expansion of slavery into new territories. Open warfare in the Kansas Territory, the panic of 1857, and John Brown's raid on Harper's Ferry further heightened sectional tensions and helped Republicans sweep elections in 1860. In 1860, the election of Abraham Lincoln, who met staunch opposition from Southern slave-owning interests, triggered Southern secession from the union.
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