OK, I'll bite.
From the Northern point of view it was not a war to free the slaves, it never was. It was a war to preserve the Union, period. An end to slavery was a fortunate outcome of the rebellion but not the reason why the North persisted. From the southern point of view, on the other hand, it was a war to defend against what they saw as a threat to their insititution of slavery.
The Emancipation Proclamation did not free the slaves up North because Lincoln lacked the authority to do so. And, contrary to popular southron belief, it didn't end slavery, it took the 13th Amendment to accomplish that. The Emancipation Proclamation merely declared those currently held as slaves to be free, and Lincoln issued it not by authority granted him as president, but by the authority granted him as Commander in Chief of the Armed Forces as a necessary measure for subduing the rebellion. Read the document, it's all in there.
Aw c'mon. You know those folks never read the documents; and if they're shown the documents, they willfully misread them. They hate that the "southern cause" was all about slavery. They'd rather cling to their myths.