Causes of the Civil War

The American Civil War (1861–1865) was the bloodiest conflict in American history, killing an estimated 620,000–750,000 soldiers. Understanding its causes is essential for the AQA GCSE History specification. The war was caused by a combination of long-term tensions over slavery, states' rights, and economic differences between the North and the South.

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The Slavery Question

Slavery was the single most important cause of the Civil War. By 1860, approximately 4 million enslaved African Americans lived in the Southern states.

Key Differences Between North and South

	North	South
Economy	Industrial; factories, manufacturing, trade	Agricultural; relied on cotton and tobacco grown by enslaved labour
Labour	Free wage labour; growing immigrant population	Enslaved labour; 4 million enslaved people by 1860
Attitude to slavery	Growing abolitionist movement; many wanted to prevent the spread of slavery to new territories	Defended slavery as essential to the economy and as a way of life; argued it was a states' right
Population	22 million (1860)	9 million (including 3.5 million enslaved people)
Urbanisation	More urbanised; cities growing rapidly	More rural; few large cities

Exam Tip: The Civil War was not simply about slavery. Examiners expect you to discuss multiple causes, including economic differences, states' rights, and the failure of political compromise. However, slavery was the root cause that connected all the others.

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States' Rights vs Federal Power

A fundamental disagreement ran through American politics from the very founding of the nation: how much power should the federal (national) government have, and how much should belong to individual states?

• The South argued that each state had the right to make its own decisions, including whether to allow slavery. This was known as states' rights.
• The North increasingly argued that the federal government had the authority to limit or abolish slavery, especially in new territories.
• Southerners feared that if the federal government could abolish slavery, it could control any aspect of state life.

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Key Events Leading to War

Date	Event	Significance
1820	Missouri Compromise	Missouri entered as a slave state, Maine as a free state; slavery banned north of the 36°30' line. Temporarily eased tensions.
1850	Compromise of 1850	California admitted as a free state; stronger Fugitive Slave Act required Northerners to return escaped slaves. Angered abolitionists.
1852	Uncle Tom's Cabin published	Harriet Beecher Stowe's novel exposed the horrors of slavery to a mass audience. Lincoln reportedly said she was "the little woman who wrote the book that started this great war."
1854	Kansas–Nebraska Act	Allowed the people of Kansas and Nebraska to decide whether to allow slavery (popular sovereignty). Led to violent clashes known as "Bleeding Kansas."
1857	Dred Scott Decision	The Supreme Court ruled that enslaved people were not citizens and had no right to sue in court; Congress could not ban slavery in territories. Outraged the North.
1859	John Brown's Raid	Abolitionist John Brown attacked the federal arsenal at Harpers Ferry, Virginia, hoping to start a slave uprising. He was captured and executed. Northerners saw him as a martyr; Southerners saw him as a terrorist.
1860	Election of Abraham Lincoln	Lincoln, a Republican who opposed the spread of slavery, won the presidential election without a single Southern electoral vote. The South saw this as proof they had lost control of the federal government.
1860–1861	Secession	Seven Southern states seceded (left the Union) before Lincoln took office. They formed the Confederate States of America with Jefferson Davis as president.
12 April 1861	Attack on Fort Sumter	Confederate forces attacked the Union fort in Charleston harbour, South Carolina. This was the first shots of the Civil War. Four more states seceded.

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The Role of Abraham Lincoln

Abraham Lincoln was elected President in November 1860 as the candidate of the Republican Party. He was not an abolitionist — he did not call for the immediate end of slavery — but he firmly opposed its expansion into new territories.

• Lincoln believed the Union must be preserved at all costs.
• His election terrified the South because it showed the North could elect a president without any Southern support.
• He famously said: "A house divided against itself cannot stand. I believe this government cannot endure, permanently, half slave and half free."

Exam Tip: Be careful not to oversimplify Lincoln's position. He opposed the spread of slavery but did not initially call for abolition. His views evolved during the war, culminating in the Emancipation Proclamation (1863).

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Key Figures

Person	Role
Abraham Lincoln	Republican President; opposed the spread of slavery; led the Union
Jefferson Davis	President of the Confederate States of America
Harriet Beecher Stowe	Author of Uncle Tom's Cabin (1852)
John Brown	Radical abolitionist; led the raid on Harpers Ferry (1859)
Dred Scott	Enslaved man whose Supreme Court case (1857) denied citizenship to Black Americans
Stephen Douglas	Senator who proposed the Kansas–Nebraska Act; debated Lincoln

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Expanded Specific Detail: Events, Numbers, Legislation

By 1860 there were approximately 3.95 million enslaved people in the United States, according to the 1860 census, concentrated in fifteen slave states; the enslaved population of South Carolina and Mississippi exceeded the free white population. The Missouri Compromise of 1820 admitted Missouri as a slave state and Maine as a free state and banned slavery north of the parallel 36°30' in the Louisiana Purchase. The Compromise of 1850, drafted by Henry Clay and steered through Congress by Stephen A. Douglas in five separate bills, admitted California as a free state, established Utah and New Mexico under popular sovereignty, abolished the slave trade in Washington D.C., and crucially strengthened the Fugitive Slave Act, which required federal officers in free states to assist in returning escaped enslaved people. Harriet Beecher Stowe's Uncle Tom's Cabin (1852) sold around 300,000 copies in its first year in the United States. The Kansas–Nebraska Act of 30 May 1854, promoted by Douglas, repealed the Missouri Compromise and opened both territories to popular sovereignty on slavery, provoking the violence of "Bleeding Kansas" (1854–1859) and the Pottawatomie Massacre of May 1856 led by John Brown. The Dred Scott v. Sandford decision of 6 March 1857 ruled that African Americans could not be citizens and that Congress had no power to ban slavery in the territories. John Brown's raid on Harpers Ferry took place on 16 October 1859; he was hanged on 2 December 1859. In the 1860 presidential election, Lincoln won 39.8 per cent of the popular vote but 180 of 303 electoral votes, carrying every free state; he was not on the ballot in ten Southern states. South Carolina seceded on 20 December 1860; six more states followed by February 1861, forming the Confederacy with Jefferson Davis inaugurated on 18 February. Confederate forces attacked Fort Sumter on 12 April 1861, beginning the war.

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Extended Worked Paragraph: Level 4/5 Model Response

Question: "Slavery was the main cause of the American Civil War." How far do you agree? (16 marks)