Philip’s first years of kingship were devoted to the discipline of his army. Hitherto most of the main battle fighting in the world had been done by footmen in formation. In the very ancient Sumerian battle-pieces we see spearmen in close order forming the main battle, just as they did in the Zulu armies of the nineteenth century; the Greek troops of Philip’s time were still fighting in that same style; the Theban phalanx was a mass of infantry holding spears, the hinder ranks thrusting their longer spears between the front-line men. Such a formation went through anything less disciplined that opposed it. Mounted archers could, of course, inflict considerable losses on such a mass of men, and accordingly, as the horse came into warfare, horsemen appeared on either side as an accessory to this main battle. The reader must remember that the horse did not come into very effective use in western war until the rise of the Assyrians, and then at first only as a chariot horse. The chariots drove full tilt at the infantry mass and tried to break it. Unless its discipline was very solid they succeeded. The Homeric fighting is chariot fighting. It is not until the last thousand years B.C. that we begin to find mounted soldiers, as distinct from charioteers, playing a part in warfare. At first they appear to have fought in a scattered fashion, each man doing his personal feats. So the Lydians fought against Cyrus. It was Philip who seems to have created charging cavalry. He caused his “companions” to drill for a massed charge. And also he strengthened his phalanx by giving the rear men longer spears than had been used hitherto, and so deepening its mass. The Macedonian phalanx was merely a more solid version of the Theban phalanx. None of these massed infantry formations was flexible enough to stand a flank or rear attack. They had very slight manœuvring power. Both Philip’s and his son’s victories followed, therefore, with variations, one general scheme of co-operation between these two arms. The phalanx advanced in the centre and held the enemy’s main body; on one wing or the other the cavalry charges swept away the enemy cavalry, and then swooped round upon the flank and rear of the enemy phalanx, the front of which the Macedonian phalanx was already smiting. The enemy main battle then broke and was massacred. As Alexander’s military experience grew, he also added a use of catapults in the field, big stone-throwing affairs, to break up the enemy infantry. Before his time catapults had been used in sieges, but never in battles. He invented “artillery preparation.”