This is a timeline of significant events leading to the American Civil War. See also Origins of the American Civil War.

+ Nat Turner leads a slave revolt in Southampton County, Virginia.
+ Responding to new Christian sensibilities, the rising importance of slave labor in the Southern cotton economy, the Nat Turner uprising, and the rise of abolitionism, Southern defenders of slavery start seeing it not as a "necessary evil," but a "positive good." + The abolitionistAmerican Anti-Slavery Society is founded. + Radical New York Democrats and anti-slavery Whigs form the Free-Soil party. It names Martin Van Buren for president and demands Wilmot Proviso. Proposed by Henry Clay and brokered by Stephen A. Douglas, it reflects solution to slavery of Northern Democrats. Southerners take wait-and-see approach; they are angered by Northern refusal to obey Fugitive Slave Law of 1850. + Harriet Beecher Stowe publishes Uncle Tom's Cabin. A forceful indictment of slavery, the novel sells roughly 500,000 copies within five years. Stiffens northern resistance to fugitive slave law. Whig party is decisively defeated in the election and fades away, abandoned by leaders and voters. + The Kansas-Nebraska Act is passed, providing that popular sovereignty in the territories should decide "all questions pertaining to slavery." It effectively repeals the Missouri Compromise.
+ In uproar against Kansas-Nebraska Act, new Republican party is formed; anti-slavery base. Includes many former Whigs and Free Soilers, and some Democrats. Sweeps fall elections in northern states. Abraham Lincoln emerges as Republican leader in Illinois
+ Know-Nothing party sweeps state and local elections in parts of North; demands purification, opposes Catholics (because of Pope), opposes corruption in local politics. The party has no real leaders and soon fades away. + The Ostend Manifesto is denounced by the free-soil press as a conspiracy to extend slavery. + Walker Tariff of 1846 is lowered still more and is supported by most southerners. It does not protect northern industry.
+ Southern opposition kills the Pacific Railway Bill of 1860.
+ Buchanan breaks with Douglas over Kansas; bitter feud inside Democratic party. + Hinton Rowan Helper publishes Impending Crisis of the South angering South.
+ Supreme Court hands down Dred Scott decision, ruling that Congress lacks the power to exclude slavery from the territories.
+ The pro-slavery Lecompton Constitution is signed in Kansas . + Lincoln and Douglas debate; Lincoln emerges as nationally known moderate spokesman for Republicans
+ William Yancey advocates a Southern confederacy. Yancey also calls for the reopening of the African slave trade at the Southern Commercial Convention. + John Brown attempts to ignite slave rebellion in Virginia by attack on federal armory at Harper's Ferry; no rebellion; captured, tried and hung; becomes martyr to North; alarms South as exemplar of fanatical Yankee abolitionist trying to start bloody race war; Republican Party disavows Brown, who had financial support from Boston + Radicals William H. Seward of New York, Salmon P. Chase of Ohio, and Simon Cameron of Pennsylvania are the leading contenders for the Republican presidential nomination. Lincoln, however, out-maneuvers his opponents. On May 16, Lincoln wins the Republican nomination at convention in Chicago.
+ The Morrill Tariff passes the House of Representatives on a strict sectional vote, supported by the north and opposed by the south; it does not pass Senate.
+ The Democratic party splits. Southerners support John C. Breckinridge. Northern Democrats and some in South support Douglas.
+ Former Whigs from the border states form the |Constitutional Union Party, nominating John C. Bell for president on a one-issue platform of national unity.
+ Four candidates as parties wage campaigns. Douglas and Lincoln compete for Northern votes. Bell, Douglas and Breckinridge compete for Southern votes.
+ Abraham Lincoln wins the 1860 election for president.
+ Secession: A special South Carolina convention declared on December 20 "that the Union now subsisting between South Carolina and other states under the name of the 'United States of America' is hereby dissolved"
+Process of secession begins.
+Last major N-S links broken as Presbyterian and Episcopal Churches split North and South
+Numerous compromise proposals are rejected; Confederacy demands complete independence and will not negotiate a return to the Union.
+Confederates capture US arsenals and forts in CSA states; General David E. Twiggs surrenders one-fourth of US Army in Texas, then joins Confederacy.
+Northern governors secretly buy arms and prepare regiments for war; CSA--apparently unaware--does not do this
+Virginia leaders negotiate with Lincoln: they will stay out of CSA but he must promise not to invade. No promise is made.
+Lee offered command of Union army; Lee says agrees unless his home state of Virginia joins the Confederacy. +Buchanan decides to keep Fort Sumter in Charleston harbor
+CSA army fired on Fort Sumter; it surrenders.
+Northern uprising--mass meetings everywhere to demand Lincoln overthrow the rebellion.
+Lincoln calls every governor for troops (75,000) to recapture Fort Sumter, via invasion of Virginia and North Carolina.
+Pennsylvania, New York, Massachusetts send troops to Washington.
+Virginia, North Carolina, Tennessee and Arkansas secede and join CSA.
+Kentucky declares neutrality. Lincoln seizes control of Missouri and Maryland; thousands of pro-CSA men under military arrest.

1787	Northwest Ordinance bans slavery in the territory; makes Ohio River the boundary between free and slave territory between the Appalachian Mountains and the Mississippi River. Mason and Dixon line remains dividing line in east.
1790	Slave population in Census: 698,000
1798	The Kentucky and Virginia Resolutions are written by Thomas Jefferson and James Madison, and are passed by the two states in opposition to the federal Alien and Sedition Acts.
1799	New York abolishes slavery
1801	Gabriel Plot frightens whites in Virginia who believe there was plot for slave uprising
1805	New Jersey abolishes slavery, the final northern state to do so
1808	Congress outlaws the international slave trade. US Navy and British Royal Navy enforce the prohibition. Some 250,000 slaves were smuggled in anyway before 1860.
1817	American Colonization Society formed to send freed slaves to Liberia. About 12,000 are sent. Society led by James Monroe, Henry Clay and other prominent slaveowners
1820	Slave population in Census: 1,538,000
1820	Missouri Compromise admits Maine as a free state, and Missouri as slave state but restricts anymore slavery north of 36° 30' line. Abrogated by Kansas-Nebraska Act of 1854.
1822	Vesey Plot frightens whites in South Carolina, who believe there was plot for slave uprising
1828	Calhoun's South Carolina Exposition and Protest outlines nullification doctrine. Calhoun threatens secession over tariffs that place South Carolina and the rest of the South at a disadvantage to the North. Twelve years later, Calhoun states that "It is our duty to force the issue slavery on the North. Had the South, or even my own State, backed me, I would have forced the issue on the North in 1835." * Calhoun also objected to the use of taxes and tariffs collected in one state being used for internal improvements to another state. //www.civilwarhome.com/statesrights.htm
1829	David Walker publishes Appeal to the Colored Citizens of the World calling on slaves to revolt
1830	Daniel Webster delivers a memorable Reply to Hayne on January 27, denouncing the notion that Americans must choose between liberty and union. "Liberty and Union, now and forever, one and inseparable!" he cries.
1831	+ William Lloyd Garrison begins publishing The Liberator.
1832	President Andrew Jackson threatens force to end threats of secession in South Carolina caused by the Nullification Crisis.
1833	+ The Compromise Tariff of 1833 ends the Nullification crisis.
1834	+ Anti-Slavery "debates" are held at Lane Theological Seminary in Cincinnati.
1836	In response to the petition campaigns of the American Anti-Slavery Society, the U.S. House of Representatives adopts a gag rule, by which all antislavery petitions presented to the House would be immediately tabled, without discussion. John Quincy Adams leads an eight year battle against the gag rule, arguing that slavery, or the Slave Power, as a political interest, threatens constitutional rights.
1839	Slaves revolt on the Amistad .
1840	Slave population in Census: 2,487,000
1844	The Methodist Episcopal Church, South breaks away on issue of slavery.
1845	The Southern Baptist Convention breaks off; does not formally endorse slavery
1845	Frederick Douglass publishes his autobiography.
1846	James D.B. DeBow establishes DeBow's Review, the leading Southern magazine warning the planter class about the dangers of depending on the North economically. DeBow's Review emerges as the leading voice for secession. The magazine emphasizes the South's economic inequality, relating it to the concentration of manufacturing, shipping, banking, and international trade in the North.
1847	Free Soilers demand the Wilmot Proviso (no slavery in Mexican cessation); growth of the "free soil" forces.
1848	+ Mexico signs the Treaty of Guadalupe Hidalgo, ceding vast tracts of land to the US. Debates center on Wilmot Proviso outlawing slavery there; it does not pass.
1850	Compromise of 1850 enacted; California admitted as free state; Texas gets paid for lands; New Mexico Territory formed, allowing slavery; no slave trade allowed in D.C.; stiffer fugitive slave law.
1851	Southern Unionists in several states defeat secession measures; Mississippi's convention denies the existence of the right to secession.
1852	+ George Fitzhugh's The Pro-Slavery Argument is published.
1854	+ Democrat Stephen A. Douglas proposes the Kansas-Nebraska Bill to open good farmland to settlement (and help railroads).
1855-1856	Violence breaks out in "Bleeding Kansas"
1856	Preston Brooks canes Charles Sumner; North takes the lesson that compromise is harder and violence is near surface. In presidential election Republican John C. Frémont crusades against slavery; the slogan is "Free speech, free press, free soil, free men, Frémont and victory!" Democratscountercrusade, warning of civil war, and win.
1857-1860	+ Short economic depression in major cities; See Panic of 1857
1857	+ George Fitzhugh publishes Cannibals All defending slavery.
1858	+ Proslavery Lecompton constitution defeated by popular referendum in Kansas in August.
1859	+ James Hammond exclaims, "Cotton is King!", meaning Europe will intervene to protect source of vital raw material
1860	Slave population in Census: 3,954,000
1860	+ Southern "fire-eaters" oppose front runner Stephen A. Douglas' bid for the Democratic presidential nomination. The Democrats begin splitting North and South.
1861	+ Seven southern states secede and form Confederate States of America. They are not recognized by U.S. government, or any government.

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