First, Lincoln didn't have 4 million under his control when he issued the Proclamation. And to get really technical, he didn't free any slaves where he did have control. Second, if all the slaves were already free, why was an Amendment necessary?
“First, Lincoln didn’t have 4 million under his control when he issued the Proclamation”
Duh. He didn’t have them under his control because the South had seceded, which is why he was fighting a war with them, which is why he had the authority to free any slaves at all.
“to get really technical, he didn’t free any slaves where he did have control.”
Not true. Aside from the border states, Virginia, New Orleans, and various other exceptions, there were in fact areas of federal control (or quasi-control) where the EP held sway. Some 20,000 or so slaves were manumitted immediately.
“if all the slaves were already free, why was an Amendment necessary?”
Is this a serious question? Because of: A) the border states and the variosu exceptions outlined in the EP, and B) to smother possible doubts as to the EP’s legitimacy after the emergency was over.