Which event is closely associated with the start of the Civil War?

The firing on Fort Sumter is widely recognized as the event that marks the official start of the Civil War in the United States. Occurring on April 12, 1861, this conflict in Charleston Harbor, South Carolina, involved Confederate forces attacking the Union-held fort. This dramatic military confrontation galvanized public opinion on both sides and led to the mobilization of troops, marking the transition from political tensions and debates over issues like states' rights and slavery into open armed conflict. The attack on Fort Sumter served as a catalyst for the formation of the Union and Confederate armies, leading to a war that would last for four years and reshape the nation. This makes it a pivotal event in American history, setting the stage for the Civil War's battles and the profound changes it would bring to the United States.