Stumbled across this article recently, a modern case for the revival of militia. For the deep Civil War reader, it's very interesting despite the author's terminal confusion over USV-type arrangements versus true militia structures.
The defining characteristic of militia is that it is local and of the USV that it is federal. The author seems to be probing an area Civil War readers would recognize: the revival of militia and the subsequent drafting of individual militiamen into federal or National Guard service during emergencies.