Origins of the American Civil War

For the Northern states, often referred to as ‘the Union’, this was a war fought primarily to restore unity to the nation and to secure the new Western Territories from slave–owners. For the Southern Confederate states, however, this was a war to assert their autonomous rights, first enshrined in the Declaration of Independence, from what they considered to be Northern aggression.

At the heart of the conflict were the interconnected issues of slavery, territorial and sectional political control. Tensions over these concerns had been present from the start the American nation. The United States began as collection of colonies who sought independence from Great Britain in the late 18th century. The problem of slavery was never clearly settled by the Founding Fathers, leading to decades of discussion, compromise and growing unrest about the future of the institution.

Detail from an 1861 map showing the products of the Southern States.

The new republic remained divided on the central question of slavery, and by the mid 19th century, the culture and economy of the Northern and Southern states appeared very different to inhabitants above and below what was termed the Mason–Dixon line, division between Pennsylvania and Maryland, marking the border between free and slave states.

As the United States opened up the west of the continent from the 1830s, debates raged over whether the new territories would be admitted to the nation as free or slave states. Increasingly, the South believed the North was blocking any westward expansion of slavery. Violent encounters, such as at that at Harper's Ferry (1859), and, crucially, the shots fired on Fort Sumter (12 April 1861), led to war, entangling other questions, particularly that of states rights, in a bitter dispute between the relatively industrialised North and the plantation-based society of the South.

Historians continue to debate the balance of causes underlying the origins of the Civil War, but the issue of slavery remains central in any explanation of the great disunion which almost destroyed the United States. It is almost impossible to imagine the Civil War erupting without the passions aroused among Northern abolitionists and those in the South who saw slave-holding as central to their way of life. The abolition of slavery itself was never a direct Union war aim until 1863 when Lincoln issued the Emancipation Proclamation, declaring freedom for over three million slaves in the South.

After four protracted years of bloody conflict, the Union eventually forced the surrender of the Confederacy on 9 April 1865, though victory celebrations were marred by Lincoln’s assassination several days later. While the Civil War did give the country, as Lincoln said, a 'new birth of freedom', it cast a long shadow on the history of the South and its legacy shaped much of the subsequent development of the American nation.

The origins of the Civil War remain a matter of great debate, with a strand of Southern collective memory emphasising the belligerence of the North and states rights, rather than the issue of slavery. The majority of professional historians, in contrast, point to the centrality of slavery as the main origin of the War, arguing that the issue was at the centre of national political debate in the years and decades before shots were fired at Fort Sumter in April 1861.

Find out more

• Etcheson, Nicole. 'The Origins of the Civil War', History Compass 3:1 (2005)
• McPherson, James M., Battle Cry of Freedom: the Civil War era (1988 and later editions).