What event sparked the start of the Civil War?

The attack on Fort Sumter is widely recognized as the event that marked the start of the Civil War. This confrontation took place on April 12, 1861, when Confederate forces fired upon the Union-held fort in Charleston Harbor, South Carolina. The bombardment of Fort Sumter represented a breaking point; it effectively signaled that diplomatic means of resolving the tensions between the North and South had failed, and military conflict had begun. The attack galvanized both the North and the South, leading to a widespread mobilization of forces and a declaration of war.

In contrast, while the election of Abraham Lincoln heightened tensions and contributed to the secession of Southern states, it was not a direct military engagement. The Dred Scott decision, a landmark Supreme Court case, inflamed sectional tensions but did not trigger hostilities. Similarly, the Kansas-Nebraska Act led to violent conflict known as "Bleeding Kansas" but precedes the actual outbreak of the war itself. Therefore, the attack on Fort Sumter is the clear catalyst that initiated the Civil War.