The more I study the uncivil war the more interesting it becomes. From what I have found it appears that Slavery was only a wedge issue at the start of the war, as the war progressed it became harder and harder for the North to justify the blood letting (read many editorials, draft riots, etc.), also the north became a butcher - 'total war' was a northern justification. The north needed to save face and came up the the idea that slavery was the real issue. Look to reconstruction to see the 'love' the north had for ex slaves. With the dead of Lincoln the country needed a myth and it created one. When we look back with a 21 century lens some like the myth even more.