What Were the Causes of the American Civil War? | History Hit

What Were the Causes of the American Civil War?

The American Civil War (1861-65) is one of the most studied periods in American history, and the conflict remains the bloodiest in American history, claiming the lives of roughly 20% of men aged between 18 and 40.

The folklore and mythology surrounding the Civil War have captured the imaginations of generations since, and the Confederate flag remains a controversial and politically powerful symbol today.

But why did America – the land of hope and dreams – erupt into such a destructive and dramatic civil war?


Following the end of the American War of Independence in 1783, the newly independent United States developed its own political structures and constitution. It also began to expand rapidly, purchasing large swathes of land from Mexico and France. As it became a bigger entity, more and more regional disparities became clear.

Not only was climate and time zone completely different between north and south and east and west, so too was the backbone of these economies. The South relied on agriculture, the West had struck gold, and the North was rapidly industrializing. These differences increasingly began to cause political and cultural tensions.

A long-standing controversy

One such tension was on the subject of slavery: a key cause of the American Civil War. The Unionist North objected to the enslavement of black people, seeing it as incompatible with the idea of a republic, and with the new constitution. By 1804, all Northern states had taken significant measures to outlaw slavery.

In contrast, the South defended slavery – not least because it was the bedrock of their society and way of life. In states where cotton, sugar and tobacco were not only extremely profitable but formed their economic core, abolishing slavery would fundamentally change the way the world worked.

Many in the South were not simply afraid for their livelihoods, but for their lives. There was a very real paranoia about newly emancipated slaves rising up in justifiable anger and hurting or killing them. Whilst this may sound dramatic, their fear was not entirely unfounded. Large numbers of whites were killed following the emancipation of slaves in Haiti.

Whilst slavery was not the only cause of these tensions, debates on the subject fed into other economic, social and political tensions too.

Stafford Plantation Mansion on Cumberland Island, Georgia.
Image credit : CC / Historic American Buildings Survey of Georgia.

State vs Federal Government

Southern states felt increasingly that their individual autonomy was being encroached on. They wanted the right to abolish federal laws they did not agree with, and increasingly began to use the threat of secession – the leaving of the Union – against the North.

In short, the South was keen to maintain agency and power as individual states, rather than completely acquiesce to central government, which many in the South felt did not represent their interests or reflect their economy.

Equally, people believed the population of Northern states was growing much faster than that in the Southern states. A fear of being a minority, and therefore losing some of their political clout, also became a driving factor.

This became further entrenched as a belief by the election of Abraham Lincoln as 16th President of the United States. Lincoln’s votes came exclusively from the North and West – not a single Southern state voted for Lincoln to become President. In fact, he was not even on their ballot papers.

This sense of exclusion and lack of power further bolstered political divisions and the Southern states’ desire to regain some agency over their lives.

Abraham Lincoln. Image credit: Anthony Berger / CC

Territorial Expansion

It was not just the lack of election of Lincoln that was the problem – it was what he represented. At this point, large swathes of the mountainous Western states were almost unsettled by whites, with only a few prospectors looking for gold or oil. The frontiers were pushing ever further into these territories.

The Northern and Southern states disagreed hotly on whether or not slavery should be taken into the western territories, and legislation surrounding slave laws in newly declared territories became a fierce point of contention.

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Lincoln’s election proved to be the point of no return. In December 1860, South Carolina formally seceded from the Union, and in the next two months, Mississippi, Florida, Alabama, Georgia, Louisiana and Texas followed.

Several states mentioned the failure of federal government in their duty to ‘slaveholding states’, arguing it was their right to hold slaves.

In his inaugural address, Lincoln declared the union to be permanently binding, and secession to be void. Shortly after, Union and Confederate forces clashed for the first time at the Battle of Fort Sumter in April 1861.


According to Lincoln, the American Civil War was always about unity, yet slavery has become recognised as one of the core causes of the war, even if political rhetoric suggests otherwise. A panel of American historians neatly summarised this, saying whilst slavery was a key cause of disunity, it was disunity which was the catalyst to war.

The Thirteenth Amendment was eventually passed by Congress in January 1865, and ratified in December the same year, which outlawed slavery, making emancipation legal and binding. Three million slaves were emancipated by this, yet their post-emancipation status was unclear.

However, slavery may have ended in name, but in reality segregation and discrimination was still enshrined in attitudes and law in many Southern states. The passing of the Jim Crow laws in the 1870s ensured that racial discrimination lived on.

Sarah Roller