It seems every so often, we have to discuss the cause of the War. Even when we all agree that every soldier had his own individual cause to fight for.
It all comes down to propaganda created by the Radical Republicans of Lincolndom. Check my sources, but Shelby Foote wrote that the the Republican Caucus of 1864 established the campaign platform for the coming election that #1 The Cause of the War was slavery.
Now my point is this, up until then, there wasn't an authorized slavery cause from the Union prospective, unless it was personal. Well now you are going to counter with the Emancipation Proclamation. But no the Emancipation Proclamation was not a slavery issue but a military decision to cripple the Southern States further. Not to make sure all slaves went free, and we all know this. We here that "Mr. Lincoln freed the slaves". Would it not be more appropriate to say Congress did that after Lincolns death.
So my point here is this. You say tomahto, I say tamayter, you aren't going to change my way of thinking I have quit trying to change yours.
Instead of talking about Slavery as a cause, lets make it an issue as to why the Republican Caucus had to make slavery "The Cause" of the War.