How is did Lincoln's view of slavery change as war progressed?

In the Summer of 1862, as Lee won a string of victories in Virginia, Lincoln feared rightly that Britain and France were close to granting recognition to the Confederates and sending military aid.

To prevent this, he issued the Emancipation Proclamation, to make the war look like a crusade against slavery (which it hadn't been), so that free nations abroad could not help the South without looking pro-slavery themselves.

This was entirely successful, and Britain and France had to adabndon their plans to help the South.