American Civil War, four-year war (1861–65) between the United States and 11 Southern states that seceded from the Union and formed the Confederate States of America.

Prelude to war

The secession of the Southern states (in chronological order, South Carolina, Mississippi, Florida, Alabama, Georgia, Louisiana, Texas, Virginia, Arkansas, Tennessee, and North Carolina) in 1860–61 and the ensuing outbreak of armed hostilities were the culmination of decades of growing sectional friction over slavery. Between 1815 and 1861 the economy of the Northern states was rapidly modernizing and diversifying. Although agriculture—mostly smaller farms that relied on free labour—remained the dominant sector in the North, industrialization had taken root there. Moreover, Northerners had invested heavily in an expansive and varied transportation system that included canals, roads, steamboats, and railroads; in financial industries such as banking and insurance; and in a large communications network that featured inexpensive, widely available newspapers, magazines, and books, along with the telegraph.

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By contrast, the Southern economy was based principally on large farms (plantations) that produced commercial crops such as cotton and that relied on slaves as the main labour force. Rather than invest in factories or railroads as Northerners had done, Southerners invested their money in slaves—even more than in land; by 1860, 84 percent of the capital invested in manufacturing was invested in the free (nonslaveholding) states. Yet, to Southerners, as late as 1860, this appeared to be a sound business decision. The price of cotton, the South’s defining crop, had skyrocketed in the 1850s, and the value of slaves—who were, after all, property—rose commensurately. By 1860 the per capita wealth of Southern whites was twice that of Northerners, and three-fifths of the wealthiest individuals in the country were Southerners.

The extension of slavery into new territories and states had been an issue as far back as the Northwest Ordinance of 1784. When the slave territory of Missouri sought statehood in 1818, Congress debated for two years before arriving upon the Missouri Compromise of 1820. This was the first of a series of political deals that resulted from arguments between pro-slavery and antislavery forces over the expansion of the “peculiar institution,” as it was known, into the West. The end of the Mexican-American War in 1848 and the roughly 500,000 square miles (1.3 million square km) of new territory that the United States gained as a result of it added a new sense of urgency to the dispute. More and more Northerners, driven by a sense of morality or an interest in protecting free labour, came to believe, in the 1850s, that bondage needed to be eradicated. White Southerners feared that limiting the expansion of slavery would consign the institution to certain death. Over the course of the decade, the two sides became increasingly polarized and politicians less able to contain the dispute through compromise. When Abraham Lincoln, the candidate of the explicitly antislavery Republican Party, won the 1860 presidential election, seven Southern states (South Carolina, Mississippi, Florida, Alabama, Georgia, Louisiana, and Texas) carried out their threat and seceded, organizing as the Confederate States of America.

In the early morning hours of April 12, 1861, rebels opened fire on Fort Sumter, at the entrance to the harbour of Charleston, South Carolina. Curiously, this first encounter of what would be the bloodiest war in the history of the United States claimed no victims. After a 34-hour bombardment, Maj. Robert Anderson surrendered his command of about 85 soldiers to some 5,500 besieging Confederate troops under P.G.T. Beauregard. Within weeks, four more Southern states (Virginia, Arkansas, Tennessee, and North Carolina) left the Union to join the Confederacy.

Britannica Quiz

Reconstruction Era Quiz

With war upon the land, President Lincoln called for 75,000 militiamen to serve for three months. He proclaimed a naval blockade of the Confederate states, although he insisted that they did not legally constitute a sovereign country but were instead states in rebellion. He also directed the secretary of the treasury to advance $2 million to assist in the raising of troops, and he suspended the writ of habeas corpus, first along the East Coast and ultimately throughout the country. The Confederate government had previously authorized a call for 100,000 soldiers for at least six months’ service, and this figure was soon increased to 400,000.