How did the Union go about really ending the slave trade? As a layman, I'd imagine that plenty of Southerners continued to hold and trade slaves after the immediate defeat of the Confederacy. How do you even begin to stop a market that was so integral to that region's survival prior to the war?
The South was occupied by the United States military forces. The war that had been raging on Southern soil for four years had already liberated a significant number of enslaved people. For the rest of them, the United States military sent detachments to plantations to proclaim liberty. Former slaves were now allied with the US army against their former owners. The real question for me is how would you envision defeated southerners continuing to hold millions of people in bondage in this situation?