I once thought poorly of Abraham Lincoln, believing the Civil War had been fought over states' rights. And states' rights lost. Once I studied the issue in depth, my perception of Lincoln as a leader and man changed dramatically.
The North did not fight the Civil War to combat slavery. They fought to keep the Union intact. The South did fight over states' rights - but the "right" in question was always slavery, and the Southern States seceded when Abraham Lincoln was elected president and the South feared losing its slaves. If you look at the Civil Rights struggle in the 1950s and 60s, you will see a reoccurence of this theme. Ergo, the Civil War was indeed fought over slavery.
When John Wilkes Booth used his derringer and bowie in Ford's Theater, he destroyed the best chance the South had for a productive reintegration with the Union. Under Andrew Johnson's leadership, the stage was set for a bitter battle among Radical Republicans, Johnson, and Southerners who would soon scapegoat blacks for the troubles in which they found themselves.
Quickly check your knowledge of this era with my study guide.