When a king achieves this or that object with the assistance of a friend who is to receive the help of his army in return later on, then he may send out of his various kinds of army--such as hereditary army, hired army, army formed of corporations of people, his friend's army and the army composed of wild tribes--either that kind of army which has the experience of all sorts of grounds and of seasons or the army of enemies or of wild tribes, which is far removed in space and time.