Causes of Sectional Conflict in Antebellum America: Key Events and Figures

Abraham Lincoln

16th president (1861-65); Republican; opposed expansion of slavery; election triggered secession; issued Emancipation Proclamation; led Union to victory.

Compromise of 1850

Package of laws resolving Mexican Cession disputes: CA admitted free, stronger Fugitive Slave Act, popular sovereignty in Utah/NM, slave trade banned in D.C.

Dred Scott Decision (1857)

Supreme Court ruled enslaved people were property, not citizens; Congress could not ban slavery in territories; invalidated Missouri Compromise and inflamed sectional tensions.

Election of 1860

Lincoln (Republican) won without Southern electoral votes; South saw his victory as a threat to slavery → secession of Deep South.

Fugitive Slave Act (1850)

Required citizens to aid in capturing escaped enslaved people; denied accused fugitives a jury trial; outraged Northern abolitionists.

Free-Soil Ideology

Belief that slavery should not expand into Western territories to protect opportunity for free white labor.

Harpers Ferry (1859)

John Brown's attempted raid on federal arsenal to spark a slave uprising; failed but intensified sectional polarization.

James K. Polk

Expansionist Democratic president; advocated Manifest Destiny; led U.S. during Mexican War; achieved huge territorial gains.

John Brown

Radical abolitionist; responsible for Pottawatomie Massacre (Bleeding Kansas) and Harpers Ferry raid; became a martyr in the North.

Kansas-Nebraska Act (1854)

Stephen Douglas's act opening Kansas & Nebraska to popular sovereignty; voided Missouri Compromise; led to Bleeding Kansas and the birth of the Republican Party.

Manifest Destiny

1840s belief that the U.S. was destined to expand across North America; justified westward expansion, Native removal, and war with Mexico.

Mexican War (1846-48)

Conflict sparked by Polk over Texas boundary; U.S. victory gained Mexican Cession (CA, NM, AZ, etc.) → major debate over expansion of slavery.

Popular Sovereignty

Voters in territories would decide slavery question; attempted compromise but led to violence in Kansas.

Republican Party (1854)

Formed by antislavery Whigs/Free-Soilers; opposed expansion of slavery; Lincoln elected as first Republican president.

Sam Houston

Leader of Texas independence movement; president of Republic of Texas; later governor who opposed secession in 1861.

Stephen A. Douglas

Illinois senator; championed popular sovereignty; author of Kansas-Nebraska Act; debated Lincoln in 1858.

Texas Annexation (1845)

U.S. annexed the Republic of Texas; contributed to tensions with Mexico and start of Mexican War.

Treaty of Guadalupe-Hidalgo (1848)

Ended Mexican War; Mexico ceded California & Southwest; U.S. paid $15 million.

Wilmot Proviso (1846)

Proposal to ban slavery in all land acquired from Mexico; never passed but symbolized rising sectional conflict.

Winfield Scott

Whig general in Mexican War; later early Civil War commander; designed Anaconda Plan.

Young America Movement

1850s Democratic movement promoting expansionism, nationalism, and American exceptionalism.