It must have been something for those officers who fought in that war.
Ulysses S. Grant had been drummed out of the army several years before Fort Sumter. He'd been stationed out in the far west, away from his family, where he had developed a bad drinking problem. His father, who had some political pull, tried getting him re-instated. The secretary of war refused the appeal. The Secretary of War's name was Jefferson Davis.
When Grant got to New York - on his way back from the west coast - he'd had to go around the horn - he called up his old classmate, Simon Buckner who had stood up for him at his wedding - and pleaded with him for some money to get a hotel and eventually get his way home to Illinois.
Buckner was the commanding officer who he defeated in the first big northern victory in the civil war - at Fort Donelson.
Those officers were so entangled back then, personally. They'd all gone to school together at West Point, knew each other as people, as individual classmates - you know -with all the things that we remember classmates for.
And then they had to fight each other. Some went south to fight, some went north. Buckner had been working in Illinois. Sherman had been teaching at a military institute in Louisiana just before the war.
In 1861, starting today a hundred and fifty years ago, they went to war with each other - in a war where men stood within plain sight of each other across open fields and shot at each other's hearts. They didn't have to be that good a shot. Without penicillin, and with tetanus, a bullet wound of any kind was often lethal. In 1865, at Appomattox Courthouse, Grant spotted another classmate, James Longstreet across the room.
Imagine what these days were like - these American officers fighting each other - then attempting to rebuild relationships after the horror. The result of the war was one real fact: the end of slavery.
There were 4 million human beings held in slavery at war's end. Four million people. That's a lot of human tragedy when you think about fathers having to watch as their daughters get treated the way the owners feel like treating them, parents having children they know will be up for sale by their owners.
It was not, as it was claimed, a war about slavery - but it was, of course. Before it was constitutional; afterward, it wasn't.
A significant result - but at what a price, a war of even classmates against each other.