Lincoln issued the Emancipation Proclamation in his position as commander-in-chief, not as president. Not to place too fine a point on the arguement, the proclamation did not end slavery in the southern states. It merely proclaimed those held as slaves to be free, and only those owned by people supporting the rebellion. Lincoln could not outlaw slavery because nothing in the Constitution prohibited it. That's why the 13th Amendment was passed. So perhaps in a way Menken was correct. The proclamation 'freed' nobody per se. But it did mean that those slaves who ran off from their owners to the safety of Union lines could not be returned to their owners, as the Fugitive Slave Laws required, because they weren't slaves anymore.