Of all the famous and infamous experiences of Lowell’s Benjamin Butler during his service as a Union General during the American Civil War, perhaps the most important was a decision he made in May of 1861, just a month into the war and just a day after he took command of Fortress Monroe. Located at Hampton Roads, Virginia, just across from Norfolk, Fortress Monroe sat at the entrance to Chesapeake Bay and was one of the few pre-war military installations in Virginia that were retained by the North in the early days of the war.

On Butler’s second day in command of Fortress Monroe, three slaves who had been forced to dig gun emplacements in the Confederate lines opposite the fort escaped and showed up at the front gate asking for asylum. Because the North was unified behind preserving the Union and not ending slavery, the Lincoln administration had scrupulously avoided the issue of what to do with slaves that came under control of the Union Army. This issue now unavoidably confronted Butler.

In today’s New York Times magazine, Adam Goodheart, whose new book “1861: The Civil War Awakening” will be published this month, has a wonderful account of how Butler made his decision and the far-reaching consequences of that decision. In the article, Goodheart describes how the slaves were brought before the new commanding general of the fort, a face that was unfamiliar to any of them. Goodheart continues:

As far as faces went, his was not – to put it mildly – a pleasant one. It was the face of a man whom many people, in the years ahead, would call a brute, a beast, a cold-blooded murderer. It was a face that could easily make you believe such things: a low, balding forehead, slack jowls and a tight, mean little mouth beneath a drooping mustache. It would have seemed a face of almost animal-like stupidity had it not been for the eyes. These glittered shrewdly, almost hidden amid crinkled folds of flesh. One of them had an odd sideways cast, as if its owner were always considering something besides the thing in front of him.

Using the reasoning skills he had refined in courtrooms across Massachusetts, Butler decided that (1) even though the Federal Fugitive Slave Law required anyone in possession of an escaped slave to return it to its rightful owner, Virginia now claimed to be a separate country and therefore Virginians no longer were entitled to the benefit of that law; and (2) that since the law of warfare allowed the seizure of the property of an opponent that was being used for warlike purposes and because these slaves (who their owners maintained were property) were being used by the Confederates to dig gun emplacements opposite the Union lines, then Butler had as much legal right to seize these slaves as contraband of war as he would have had to seize a Confederate shipment of muskets. Butler decreed that the escaped slaves would not be returned but would be held by the Union forces as “contraband of war.”

While Butler’s decision was not embraced by Washington, neither was it overruled and almost tacitly, the “contraband of war” logic became Union Army doctrine. Word quickly spread throughout the slave states and soon tens and then hundreds of thousands of men, women and children who had been held in bondage came streaming into Union lines in a tide that was irreversible.

By his decision at Fortress Monroe, Ben Butler redefined the American Civil War and profoundly changed our nation’s history.