Origins of the Civil War
One of the main causes for the Civil War was slavery. A contentious issue between North and South was the expansion of slavery into western territories. Southern slave owners held that restricting slavery would violate the principle of states' rights, whereas many Northerners believed popular sovereignty should serve as a barometer for the expansion of slavery, and some even believed slavery should be abolished completely.
Abraham Lincoln won the 1860 presidential election without being on the ballot in 10 Southern states. Lincoln’s victory triggered declarations of secession by seven slave states in the Deep South even before he took office. Nationalists refused to recognize the secessions, and the U.S. government in Washington refused to abandon its forts in Confederate territory. War began in April 1861 when the Confederates attacked Fort Sumter, a major U.S. fortress in South Carolina.
Disunion Sparks War
As a panel of historians emphasized in 2011, "while slavery and its various and multifaceted discontents were the primary cause of disunion, it was disunion itself that sparked the war." States' rights and the tariff issue became entangled in—and intensified by—the slavery issue. Other important factors were party politics, Southern and Northern nationalism, expansionism, sectionalism, economics, and modernization during the antebellum period.
The United States had become a nation of two distinct regions. The free states in New England, the Northeast, and the Midwest had rapidly growing economies based on family farms, industry, mining, commerce, and transportation, with a large and quickly growing urban population. Their growth was fed by a high birth rate and large numbers of European immigrants, especially Irish, British, and Germans. The Southern economy, on the other hand, was dominated by the plantation system, which in turn relied heavily upon the continued institution of slavery. The Southwest experienced some rapid growth due to high birth rates and high migration from the Southeast, but it had a much lower immigration rate from Europe. The South also had fewer large cities and few manufacturing hubs, except in border areas. Slave owners controlled the politics and economics of the region, though about 70 percent of Southern whites owned no slaves and were primarily engaged in subsistence agriculture.
Overall, the Northern population was growing more quickly than the Southern population, which made it increasingly difficult for the South to continue to exert influence over the national government. By the time of the 1860 election, the heavily agricultural Southern states as a group had fewer Electoral College votes than the rapidly industrializing Northern states. Southerners felt a loss of federal interest in their proslavery political demands. This provided the very real basis for Southerners' concern over the relative political decline of their region in relation to the North’s growing population and industrial output.
As sectional politics became increasingly virulent and hostile, the collapse of the old Second Party System in the 1850s hampered efforts of politicians to reach further compromises. The Kansas-Nebraska Act of 1854 outraged too many Northerners and led to the formation of the Republican Party, the first major party with no appeal in the South. Meanwhile, the industrializing North and agrarian Midwest became increasingly committed to the economic ethos of industrial capitalism.
Private citizens and politicians, including some prominent Southerners, had long been vocal about the caustic damage that the institution of slavery had on the nation. In 1840, the leaders of the newly formed Republican Party denounced slavery as morally repugnant and downright evil. Defenders of slavery, conversely, contended that slavery was a necessity and that slaves actually benefited from the arrangement. Increasingly, these ideological lines were perceived as ones that could not be reconciled peacefully, and the specter of war loomed larger over the country.