That's kinda funny. I've always read that passage to mean, those are the types of armies you don't want to be fighting against, since the best victory is victory where you don't have to fight at all and the opposing side just gives up. I never thought of it as advice to put your own people in a corner, so they have no choice but to fight their way out. I suppose morale had better be high, or else instead of "Prepare for glory", one can "prepare for slaughter."