Answer: It was an attempt to free only the slaves in the Confederacy, not the Border States or areas under Union control.
Step-by-step explanation:
The Emancipation Proclamation of 1863 by President Lincoln freed the slaves in the Confederate states. This made the war about slavery and therefore ensured that European countries did not support the Confederacy and that the Union ranks increased as African Americans signed up for the war.
Sadly the proclamation did not free the enslaved people who were in the Border states or in areas under Union control because the President did not want these areas to join the Confederacy.