How did the Civil War change from a limited war to preserve the union to a war to abolish slavery?

Yeah, its homework help, I just need some names of people and places to set me in the right direction if you want to help. I am completely lost on this one because there's so many events and I am not sure which ones really would make the cut for changing the war into a fight against slavery from a civil war about having a union. Thank you.|||Lincoln's Emancipation Proclamation made the Union cause as one to abolish slavery. With the Proclamation -- Britain, which was anti-slavery, would no longer give any thought of recognizing the Confederacy.





From Rhode's History of the Civil War


http://www.bartleby.com/252/pages/page17…





But was the sentiment of the plain people, the mass of steady Republicans and war Democrats, ripe for an edict of freedom? Again, the possibility that the policy might alienate the border slave States which had clung to the Union was in Lincoln’s mind a serious objection; “but the difficulty was as great not to act as to act.” On the other hand, emancipation would help him in Europe. England and France could not recognize the Southern Confederacy when the real issue between the two sections was thus unmasked. Yet there was reason to fear that an avowed war against slavery would revive the opposition of the Democrats and give them a “club” to use against the administration; but the President did not regard this an objection of great moment, since party opposition in the North must be expected in any event. In sum, it was only by turning the question over and over in his mind that he finally settled his doubts. He believed that a proclamation of freedom was a military necessity and that the plain people of the North would see this necessity even as he did.|||Which civil war?





If you mean the American civil war - say so because in history there has been hundreds of civil wars.