What event is associated with the failure of compromise efforts leading to additional secession?

The event associated with the failure of compromise efforts leading to additional secession is the firing on Fort Sumter. This event marks the start of the American Civil War in April 1861 and is significant because it represented a point of no return in the escalating tensions between the Northern states (the Union) and the Southern states (the Confederacy). Prior to this confrontation, various political efforts were made to maintain peace and prevent secession, including compromises like the Missouri Compromise and the Compromise of 1850. However, these efforts ultimately proved ineffective, especially as the Southern states began to secede from the Union after Lincoln's election in 1860. The attack on Fort Sumter galvanized both sides and demonstrated that peaceful negotiations had failed, leading to a full-scale war. This event encapsulates the breakdown of dialogue and the solidification of conflict, setting the stage for a dramatic and violent period in American history.