You are quite correct as to the origin of the quote. My point was that the North was concerned with labor just as the South was but in different ways. Moral objection to slavery wasn't a Northern banner.
It's really very simple. The south seceded to protect slavery from the threat to it that they saw in Lincoln's election. The north went to war to preserve the union and to avenge the attack on Sumter. But in the end, you can't deny the obvious--that the war ended slavery.