Key Events and Figures in the Lead-Up to War

Why compromise over slavery broke down

As the United States expanded westwards, the question of whether slavery would spread into new territories repeatedly threatened national unity. A territorial settlement could temporarily reduce disagreement, but it did not resolve the underlying conflict over slavery.

The Missouri Compromise of 1820 tried to preserve the balance between slave states, where slavery was legal, and free states, where it was prohibited. It provided for Missouri to enter as a slave state and Maine as a free state, so neither side gained an advantage in the number of states.

It also prohibited slavery north of the line of latitude 36°30′ in the remainder of the Louisiana Territory, the land acquired from France in the Louisiana Purchase. Missouri was an exception: it could permit slavery even though it lay north of that line. This was therefore a rule for a particular area of western territory, not a nationwide boundary between slavery and freedom.

The settlement paired a slave state with a free state and drew a geographical limit on slavery’s expansion. During the 1850s, however, political decisions and a Supreme Court ruling dismantled that territorial restriction.

The Kansas–Nebraska Act turned disagreement into violence

The Kansas–Nebraska Act of 1854 repealed the Missouri Compromise’s territorial restriction. It allowed settlers in Kansas and Nebraska to decide whether to permit slavery through popular sovereignty. Stephen Douglas supported this approach: instead of Congress imposing a territorial restriction, the inhabitants would decide.

This reopened the possibility of slavery in territory where the Missouri Compromise had prohibited it. It also created a practical problem: whoever controlled the vote could determine the territory’s future. Pro-slavery and anti-slavery supporters therefore moved into Kansas to influence the outcome.

Unfair election practices produced a pro-slavery legislature, while anti-slavery opponents established a rival government at Lawrence. The territory was no longer simply debating slavery; competing groups claimed political authority and used force against one another.

In May 1856, a pro-slavery group attacked Lawrence, burning buildings and destroying the printing presses of an abolitionist newspaper. In retaliation, John Brown and his allies murdered five pro-slavery men. The wider conflict became known as Bleeding Kansas. It showed that popular sovereignty had not delivered a peaceful settlement.

The Act also divided the Democratic and Whig parties into northern and southern factions. The Whigs declined, while the new Republican Party brought together opponents of slavery’s expansion. Disagreement over slavery was weakening national political parties that had previously helped hold the country together.

Dred Scott weakened the possibility of a territorial settlement

In 1857, the Supreme Court ruled against Dred Scott, an enslaved man who had sought freedom after living in places where slavery was prohibited.

The Court denied Scott citizenship and the right to sue in federal court. It also declared the Missouri Compromise’s restriction unconstitutional, treating enslaved people as property and ruling that Congress could not prohibit slavery in the territories.

The Kansas–Nebraska Act had already repealed the restriction in 1854; the Dred Scott ruling went further by denying Congress’s constitutional authority to impose such a ban. Northern opponents of slavery’s expansion could no longer rely on Congress’s territorial restrictions, while many white southerners welcomed the ruling. The decision deepened divisions within the Democratic Party and strengthened the appeal of the Republicans.

John Brown’s raid increased fear and mistrust

Brown was an abolitionist who believed violence could be used to destroy slavery. His actions in Kansas had already demonstrated his willingness to kill for that cause.

On 16 October 1859, Brown and 21 followers attacked the federal arsenal at Harpers Ferry, hoping to seize weapons and arm enslaved people who would join an uprising. His plan failed. Local resistance, militia and US Marines overwhelmed the raiders, and Brown was captured. Convicted of murder, treason and inciting a slave rebellion, he was hanged on 2 December 1859.

The raid’s significance was much greater than its military success. Many northern abolitionists treated Brown as a martyr: someone who had died for a just cause. For many white southerners, the attack appeared to confirm that northern opposition to slavery threatened their lives as well as their property. Fear of further uprisings increased.

These reactions widened the gulf between North and South. Brown did not end slavery through his raid, but he made trust and peaceful compromise harder to sustain. His supporters’ admiration should not, however, be treated as the view of every northerner.

Lincoln’s election became the trigger for secession

Abraham Lincoln opposed the expansion of slavery into new territories, while accepting its continued existence where it was already established. His debates with Douglas in 1858 brought this position to national attention. Although Lincoln lost that Senate contest, he gained prominence as a Republican politician.

In the 1860 presidential election, the Democrats split. Northern Democrats supported Douglas, while southern Democrats nominated John C. Breckinridge. John Bell also stood for the Constitutional Union Party. This division among Lincoln’s opponents helped him win: he secured about 40% of the popular vote and 180 electoral votes.

Many white southerners interpreted a Republican victory as a threat to slavery and their political influence. Even though Lincoln had not promised immediate abolition in existing slave states, they feared that preventing slavery’s expansion would ultimately endanger its survival.

South Carolina seceded on 20 December 1860. By early February 1861, seven states in total had left the Union and formed the Confederate States of America. Lincoln’s election was therefore a trigger for secession, but the reaction depended on years of conflict over slavery, territorial expansion and political power.

Jefferson Davis gave secession a national leadership

Jefferson Davis had served as US Secretary of War and as a senator, where he defended slavery. He was therefore an experienced national politician, not simply a military figure who appeared when war began.

After Mississippi seceded, Davis resigned from the Senate on 21 January 1861. He initially offered his services to Mississippi’s military, but was chosen to lead the new Confederacy and inaugurated as its president on 18 February 1861.

Davis believed that secession was constitutional. By accepting the presidency, he helped give the seceding states a common government and leadership. The dispute was now between Lincoln’s claim to preserve one United States and a Confederate government claiming separate independence. Davis did not initiate every state’s withdrawal, but his leadership helped turn those withdrawals into an organised challenge to the Union.

Fort Sumter turned secession into war

Lincoln took office on 4 March 1861, after the first seven states had already seceded. The immediate problem was whether the Confederacy or the United States would control federal property within the seceded states.

At Fort Sumter, in Charleston harbour, US troops were running short of supplies. Lincoln decided to send supplies without reinforcements, seeking to maintain the federal position without starting an attack. The Confederate government would not permit the resupply, and its forces demanded the fort’s evacuation.

When the federal commander refused, Confederate forces opened fire on 12 April 1861. The fort surrendered the following day. Lincoln then called for 75,000 volunteers to suppress the rebellion, and four more states subsequently seceded.

Lincoln and Davis thus represented incompatible political aims: preserving the Union and maintaining Confederate independence. Their leadership mattered, but the outbreak of war grew from the earlier collapse of compromise, escalating violence and southern fears about slavery’s future.