British wags & wit notwithstanding, that was the US law -- absent a Constitutional amendment Lincoln had no authority to abolish slavery in Union states.
But Congress could & did abolish slavery in Washington DC, and in western territories.
It could also declare slaves in Confederate states as "Contraband of war", which it did.
Union states could also abolish slavery on their own, which all but two did.
That left only Delaware and Kentucky with slavery still lawful, but they had very few slaves to begin with and by 1865 most of them had been freed by their "masters" or had run off.
The 13th Amendment just made Constitutional & permanent what had already happened, long before.
He never did have the right to do that, but like a dictator, he did it anyway, and then proclaimed his methods legal.
The 13th Amendment just made Constitutional & permanent what had already happened, long before.
The 13th amendment was the first true corruption of the US Constitution because it was passed by lies, force and trickery instead of a valid ratification process.
You don't get to pick your own electorate when the real people disagree with you. That is invalid legally and invalid morally.
But it is what a dictator does.