Final answer:
The Emancipation Proclamation freed slaves in rebellious areas and had strategic and diplomatic implications.
Step-by-step explanation:
The Emancipation Proclamation, issued by Lincoln, freed the slaves in the areas still in rebellion against the Union. This document was a military strategy aimed at depriving the Confederate states of their labor force and weakening their resources during the Civil War. Additionally, it had the effect of discouraging Great Britain from supporting the Confederacy, as the war was now officially about slavery.