[JamesP81]

What I was trying to get at was that most military units that fought were regionally (State) provided. And those who fought side-by-side were mostly all from the same state or sub region in a state or near a major river artery. This is nothing like todays military, where any random selection of 10 soldiers from a given unit is highly likely to consist of men from 9 or more States. A military this integrated just couldn't break down into a North and South and go at it today. Nor could we grow it 250 times in size to fight ourselves.

There is one detail you are forgetting. Over half of our total military power is concentrated in the National Guard, which is raised from within States.

[Diplomat]

Good point, thank you. I should have remembered watching a TV show about an Ohio and a New York National Gaurd unit suffering heavy casualities as a unit in Iraq.