Cary got down to business. “I am informed,” he said, “that three Negroes belonging to Colonel Mallory have escaped within your lines. I am Colonel Mallory’s agent and have charge of his property. What do you mean to do with those Negroes?”“I intend to hold them,” Butler said."Contraband". This term turned out to be a masterstroke. Conservatives could rest easy that escaped slaves were not being set free, merely being held until the end of the war. Liberals could be satisfied that slaves were not being returned. Yet, it changed conditions on the ground, causing hundreds of thousands of slaves to make to it to union camps where they did a lot of menial labor, freeing the soldiers to fight. In turn, all those blacks living peaceably quieted many Southerners' fears and allowed for Lincoln's Emancipation declaration.
“Do you mean, then, to set aside your constitutional obligation to return them?”
Even the dour Butler must have found it hard to suppress a smile. This was, of course, a question he had expected. And he had prepared what he thought was a fairly clever answer.
“I mean to take Virginia at her word,” he said. “I am under no constitutional obligations to a foreign country, which Virginia now claims to be.”
“But you say we cannot secede,” Cary retorted, “and so you cannot consistently detain the Negroes.”
“But you say you have seceded,” Butler said, “so you cannot consistently claim them. I shall hold these Negroes as contraband of war, since they are engaged in the construction of your battery and are claimed as your property.”
Adam Goodheart argues that the inspired off-the-cuff, lawyerly argument by Butler brought down slavery. It sounds very cool. The book is on my wish list.