In the 1860 presidential election, Republicans, led by Abraham Lincoln, opposed the expansion of slavery into US territories. Lincoln won, but before his inauguration on March 4, 1861, seven slave states with cotton-based economies formed the Confederacy. The first six to secede had the highest proportions of slaves in their populations, a total of 48.8% for the six. Outgoing Democratic President James Buchanan and the incoming Republicans rejected secession as illegal. Lincoln's inaugural address declared his administration would not initiate civil war. Eight remaining slave states continued to reject calls for secession. Confederate forces seized numerous federal forts within territory claimed by the Confederacy. A peace conference failed to find a compromise, and both sides prepared for war. The Confederates assumed that European countries were so dependent on "King Cotton" that they would intervene; none did and none recognized the new Confederate States of America.
Hostilities began on April 12, 1861, when Confederate forces fired upon Fort Sumter, a key fort held by Union troops in South Carolina. Lincoln called for each state to provide troops to retake the fort; consequently, four more slave states joined the Confederacy, bringing their total to eleven. The Union soon controlled the border states and established a naval blockade that crippled the southern economy. The Eastern Theater was inconclusive in 1861–62. The autumn 1862 Confederate campaign into Maryland ended with Confederate retreat at the Battle of Antietam, dissuading British intervention. Lincoln issued the Emancipation Proclamation, which made ending slavery a war goal.
Causes of secession
The causes of the Civil War were complex and have been controversial since the war began. The issue has been further complicated by historical revisionists, who have tried to offer a variety of reasons for the war. Slavery was the central source of escalating political tension in the 1850s. The Republican Party was determined to prevent any spread of slavery, and many Southern leaders had threatened secession if the Republican candidate, Lincoln, won the 1860 election. After Lincoln had won without carrying a single Southern state, many Southern whites felt that disunion had become their only option, because they felt as if they were losing representation, which hampered their ability to promote pro-slavery acts and policies.
The slavery issue was primarily about whether the system of slavery was an anachronistic evil that was incompatible with Republicanism in the United States, or a state-based property system protected by the Constitution. The strategy of the anti-slavery forces was containment — to stop the expansion and thus put slavery on a path to gradual extinction. To slave holding interests in the South, this strategy was perceived as infringing upon their Constitutional rights. Slavery was being phased out of existence in the North