The US Civil War and Reconstruction, 1820–77 (Cambridge 0470 and 2147)

Key question 1.4 asks why the United States went to war with itself in 1861 and whether the war changed anything. Cambridge sets the content as the causes and consequences of the Civil War from 1820 to 1877: differences between North and South, slavery and abolitionism, the 1860 election and secession, the reasons for the North’s victory, the role of Lincoln, and Reconstruction. The question is also the prescribed Paper 2 topic for the November 2025 and June 2026 series, so it needs both essay knowledge and source practice.

Where this fits in 0470 and 2147

Key question 1.4 is one of six in Core Content Option A (“The nineteenth century: the development of modern nation states, 1848–1914”). The IGCSE 0470 and O Level 2147 syllabuses for 2024–2026 use identical wording for it. On Paper 1 it can appear as a three-part structured question; on Paper 2 it is examined through sources when Cambridge prescribes it for a series. The overview of the whole option is in the Nineteenth Century IGCSE study guide and the O Level equivalent.

Syllabus coverage

The four official focus points are:

1. How far did slavery cause the Civil War?
2. What was the significance of Lincoln’s election as president?
3. Why was the North able to win the war?
4. Did the war change anything?

The specified content runs 1820–77: differences between North and South; slavery, slave states and free states, abolitionism; the 1860 election and secession of the Southern states; reasons for the North’s victory and the South’s defeat; the role of Lincoln; Reconstruction and the extent of its success.

How were the North and the South different?

By 1860 the two sections had grown apart economically and socially.

	North	South
Economy	Industry, commerce, small family farms, growing cities	Plantation agriculture, above all cotton, also tobacco and sugar
Labour	Free wage labour, large-scale European immigration	Around four million enslaved people in 1860
Population (1860)	About 22 million in the Union states	About 9 million in the Confederate states, over a third of them enslaved
Tariffs	Wanted protective tariffs for industry	Opposed tariffs that raised the cost of imports
Politics	Growing belief that Congress could limit slavery’s spread	“States’ rights”: the states, not Congress, should decide on slavery

The tariff quarrel had already produced the Nullification Crisis of 1832–33, when South Carolina declared federal tariffs void inside the state. But it was settled by compromise, which is why most historians see tariffs as a secondary cause.

How far did slavery cause the Civil War?

Almost every crisis between 1820 and 1860 was about whether slavery would spread into the new western territories.

• Missouri Compromise (1820): Missouri entered as a slave state and Maine as a free state, keeping the balance in the Senate; slavery was banned in the rest of the Louisiana Purchase north of latitude 36°30′.
• Abolitionism: William Lloyd Garrison’s newspaper The Liberator (from 1831), the speeches and writing of the formerly enslaved Frederick Douglass, the Underground Railroad (Harriet Tubman) and Harriet Beecher Stowe’s novel Uncle Tom’s Cabin (1852) turned many Northerners against slavery and convinced Southerners that the North meant to destroy it.
• Compromise of 1850: after the Mexican War (1846–48) added vast territory, California joined as a free state, but a much stricter Fugitive Slave Act forced Northern officials to help return people who had escaped slavery, which angered the North.
• Kansas–Nebraska Act (1854): Stephen Douglas let settlers decide by “popular sovereignty”, repealing the 36°30′ line. Violence between pro- and anti-slavery settlers (“Bleeding Kansas”) followed, and the new Republican Party formed to oppose slavery’s expansion.
• Dred Scott decision (1857): the Supreme Court ruled that Congress could not ban slavery in the territories and that Black Americans were not citizens.
• John Brown’s raid on Harpers Ferry (1859): an attempt to start an armed rising of enslaved people. Brown was hanged, but many Northerners treated him as a martyr, which horrified the South.

Judgement: slavery was the underlying cause, because the economic and states’-rights arguments were themselves mostly arguments about slavery. A balanced answer still explains how the breakdown of the old two-party system and the failure of compromise turned a long dispute into war.

Why did Lincoln’s election lead to secession?

In November 1860 the Democrats split between Stephen Douglas (North) and John Breckinridge (South), and John Bell stood for the Constitutional Union Party. Abraham Lincoln won with about 40% of the popular vote and a majority in the Electoral College, without carrying a single Southern state. He promised not to touch slavery where it already existed, but he opposed its spread.

Southern leaders concluded that they had lost control of the federal government. South Carolina seceded on 20 December 1860; by February 1861 seven states had formed the Confederate States of America, with Jefferson Davis as president. When Confederate forces fired on Fort Sumter on 12 April 1861 and Lincoln called for volunteers, four more states left, making eleven. The border slave states of Delaware, Maryland, Kentucky and Missouri stayed in the Union.

Why was the North able to win the war?

• Resources: a much larger population, most of the country’s factories and railways, and far greater food production.
• The blockade: the Union navy gradually closed Southern ports, cutting cotton exports and imports of weapons (“Anaconda Plan”).
• Southern diplomacy failed: the South hoped “King Cotton” would force Britain and France to recognise it; neither did.
• Turning points of 1863: the Emancipation Proclamation (announced after Antietam in September 1862, in force from 1 January 1863) made the war a war against slavery and helped keep Britain out; in July 1863 Union victories at Gettysburg and Vicksburg ended Lee’s invasion of the North and gave the Union the Mississippi.
• Generals and strategy: Ulysses S. Grant’s pressure on Lee in Virginia and William T. Sherman’s capture of Atlanta (September 1864) and “March to the Sea” destroyed the South’s capacity to fight.
• African American soldiers: about 180,000 served in the Union army.

The South had real strengths: it only had to defend, and it had skilled commanders such as Robert E. Lee and “Stonewall” Jackson. Lee surrendered at Appomattox Court House on 9 April 1865.

The role of Lincoln

Lincoln kept the border states loyal, chose generals who would fight (eventually Grant), turned the war’s purpose towards emancipation at the right moment, and won re-election in 1864. He was assassinated by John Wilkes Booth on 14 April 1865 and died the next day.

Did the war change anything? Reconstruction, 1865–77

Change	Limits
13th Amendment (1865) abolished slavery	Southern “Black Codes” (1865–66) restricted freed people’s lives
14th Amendment (1868) gave citizenship and equal protection	Courts and later governments weakened it
15th Amendment (1870) banned denying the vote on grounds of race	Violence, intimidation and later literacy tests and poll taxes kept most Black Southerners from voting
Freedmen’s Bureau (1865) built schools and helped freed people	Most freed people had no land and became sharecroppers
Black men elected to office, e.g. Hiram Revels to the Senate (1870)	The Ku Klux Klan, founded 1865–66, used terror against them

President Andrew Johnson’s lenient approach clashed with the Radical Republicans in Congress, who passed the Reconstruction Acts of 1867 and impeached Johnson in 1868 (he was acquitted by one vote). Northern interest faded, and under the Compromise of 1877 Rutherford B. Hayes became president and the last federal troops left the South. White “Redeemer” governments then took back control.

Judgement: the war preserved the Union and ended slavery, a revolutionary change, but Reconstruction failed to secure equal rights for African Americans, which is why most historians call it only a partial success.

Frequently asked questions

What was the main cause of the American Civil War? The spread of slavery into the western territories. Disputes over states’ rights and tariffs mattered, but they were closely tied to protecting slavery.

Why did the South secede after the 1860 election? Lincoln won without any Southern votes on a platform of stopping slavery’s expansion, so Southern leaders believed slavery would eventually be destroyed if they stayed in the Union.

Why did the North win? Its larger population, industry and railways, the naval blockade, the failure of Southern diplomacy, and better strategy from 1863 under Lincoln, Grant and Sherman.

Was Reconstruction a success? Partly. Slavery was abolished and the 14th and 15th Amendments were passed, but by 1877 federal protection had been withdrawn and most freed people lacked land, votes and safety.

Related resources

• US Civil War revision notes
• US Civil War practice questions

Official syllabus

Cambridge IGCSE History 0470 syllabus for 2024, 2025 and 2026, Core Content Option A key question 4 (focus points, specified content and the Paper 2 prescribed-topic table) — cambridgeinternational.org. The Cambridge O Level History 2147 syllabus for the same years sets the same key question — cambridgeinternational.org.