MERCENARIES AND MILITARY VIRTUE by Jerry Pournelle
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After all, it should be fairly clear that no one fights purely for money; that anyone who does is probably not worth hiring. As Montesquieu put it, “a rational army would run away.” To stand on the firing parapet and expose yourself to danger; to stand and fight a thousand miles from home when you’re all alone and outnumbered and probably beaten; to spit on your hands and lower the pike, to stand fast over the body of Leonidas the King, to be rear guard at Kunu-ri; to stand and be still to the Birkenhead drill; these are not rational acts.
They are often merely necessary.
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