I always believed, however, that he had been a cheap clerk in a small dry-goods store, a third or fourth rate book-keeper, or something similar.

Imagine, if you please, one such, who never had brains or self-command sufficient to control himself, placed in command of thirty-five thousand men.

Being a fool he could not help being an infliction to them, even with the best of intentions, and Wirz was not troubled with good intentions.
I mention the probability of his having been a dry-goods clerk or book-keeper, not with any disrespect to two honorable vocations, but because Wirz had had some training as an accountant, and this was what gave him the place over us.

Rebels, as a rule, are astonishingly ignorant of arithmetic and accounting, generally.

They are good shots, fine horsemen, ready speakers and ardent politicians, but, like all noncommercial people, they flounder hopelessly in what people of this section would consider simple mathematical processes.