Which was most closely related to the end of the civil war?

The end of the Civil War in the United States was most closely related to the Union's military victories, particularly the surrender of General Robert E. Lee's Confederate Army at Appomattox Court House on April 9, 1865. This surrender marked a significant turning point, as it effectively signaled the collapse of the Confederacy. Additionally, the Union's control over key territories and resources, combined with the weakening morale and resources of the Confederate states, played crucial roles in bringing the conflict to a close.