The Civil War: Even today, it is arguably the most divisive subject in American history. Why did the southern states secede from the Union? What did the north hope to achieve by fighting against the south? Was Abraham Lincoln really an abolitionist? Why is Ulysses S. Grant the most famous Union general, when he didn't take command of all the Union armies until near the very end of the war? How did Robert E. Lee end up having to deal with issues left unresolved by George Washington's will, and was he a hero or a traitor?