People who have more brains that God gave a rutabaga understand that the Three-Fifths Compromise was an accomplishment by the Abolitionists to give the slave states LESS power in Congress by reducing the number seats in the House they'd get by 40%.  More power to the slave states would have meant less power to black people enslaved in those states.

And, by the way, it wasn't illegal to secede.  The New England states (and New York) considered seceding for ten years, and no one ever suggested they couldn't.  Ending Slavery wasn't Lincoln's objective; collecting taxes from the South was.  It was only later than he made freeing the slaves an issue by issuing the Emancipating Proclamation, which didn't actually free any slaves, because it only applied to the Confederate States, who didn't recognize his authority.  The Slaves weren't freed until the ratification of the 13th Amendment.  Tens of thousands of Union soldiers deserted when Lincoln issued that proclamation.