Wasnt the War really over slavery?
The question is too ambiguous to do it justice, and that is why Northern historians and politicians try to keep it that way. They never come out and say that the North fought the war out of a sense of morality and a belief in racial equality, because it is easily refuted. They try to pass this fiction off as truth by insinuation rather than an overt statement to that effect, knowing it usually will not be challenged.
