I must say that I've always accepted and indeed pictured Alexander leading cavalry during the battle, probably because that is what I've read in books by modern authors. Checking some of my books I find that John Maxwell O'Brien has Alexander in command of the Companion Cavalry on the left; Peter Green says, "The command of the heavy cavalry on the extreme left wing, opposite the Sacred Band, went to Alexander"; even earlier works such as that of Ulrich Wilcken indicates that "The offensive on the left wing and the command of the cavalry he entrusted to his son Alexander, then eighteen . . ."(Page 154) The battlefield lay to the east of Chaeronea between rising ground on the south and southwest and the river Cephissus, which flows to the southeast. (Page 155) Thus two natural barriers afforded protection to the flanks of the allied Greek line, especially on the right where the Theban Sacred Band was posted alongside the river. Philip commanded one wing facing the Athenians, apparently on the Macedonian right, while Alexander - assisted by Philip's most notable generals - opposed the Boeotians on the left. Since there was no place for cavalry on the flanks and no mention of them is made in the admittedly brief battle descriptions, their role is unknown and must consequently be conjectured or omitted. On the other wing Alexander is said to have been the first to attack the Sacred Band and to break through the continuity of the enemy formation. The three hundred men of the Sacred Band fought and died on the spot. After the battle Philip saw them lying where they had faced the sarissas of the Macedonians and admired their courage. These events on the allied right seem to be confirmed by the modern excavation of the Macedonian burial mound containing sarrissas in a location consistent with mention of it by Plutarch.
A more fundamental question about Chaeronea is whether Alexander was commanding cavalry or infantry. In spite of the absence of clear evidence from the ancient sources, the majority of modern historians is convinced that Alexander was leading cavalry during the battle, apparently basing their judgment on (Page 156) his later use of the mounted arm in Asia.(1) A satisfactory argument against cavalry, however, is provided by P. A. Rahe, who points out that "the inability of ordinary Greek cavalry to charge through the phalanx had nothing to do with any deficiency in equipment or tactics. The problem lay with the horse. A horseman can charge into a mob, but only if those in his path give way before him. If those in the crowd link arms and stand their ground, the horse will shy," and goes on to say that "the effect of shock cavalry is psychological not physical."(2) Buckler, apparently independently, reached the same conclusion, emphasizing the fact that no ancient source mentions cavalry at the battle.(3) Perhaps most telling is Plutarch's statement that the Sacred Band faced Macedonian sarissas, a weapon that the ancient sources never associate with the Macedonian regular cavalry.
These arguments should be sufficient to cast serious doubt on the claim that cavalry broke into the Sacred Band at Chaeronea. Indeed, precisely because this elite Theban unit of heavy infantry fought and died where it was posted in the battle line, it is more likely to have faced infantry rather than cavalry. The sarissa-bearing Macedonian phalanx would have presented a dense array of spearpoints that was essentially impenetrable, and when individuals fell wounded, others moved up from behind. The much looser formation of cavalry would have made it easier for the steadfast Thebans to parry lance thrusts as well as to injure horses but more difficult for that cavalry to inflict intense slaughter in a confined space. When cavalry kill large numbers of infantry, it is usually done against men in flight. In 326, even against Mallian infantry in India, Alexander was unwilling to bring his cavalry to close quarters until his own foot had arrived, at the sight of which the Mallians turned and fled.
(The following are just three of the most interesting footnotes to the above.)
(1) AG 16 is typical: "Alexander led the cavalry charge at Chaeronea." See also Markle (1978) 490-91. Bosworth, on the other hand, states that "in the plain of Chaeronea, the Macedonian phalanx proved its superiority over traditional hoplite forces." CE 16.
(2) Rahe (1981) 84-87, quote from 85-86. Rahe's argument rests largely on Keegan (1977) 153-59, whose sound observations have, I think, rescued the cavalry charge from the excesses of Hollywood film makers. Any horse that is not in an uncontrollable frenzy will respond to the instinct for self-preservation when it faces a barrier. If one or more horses could be forced to strike unyielding infantry, others might follow under the influence of the herd instinct, but the net destruction to one's cavalry force would be unacceptable.
(3) Buckler (1990) 75-80. In spite of the evidence the story of Alexander's cavalry charge at Chaeronea has taken on a life of its own, appearing in most general histories of Greece and most recently in the National Geographic. Alexander (2000) 48.
See my next post for the ancient sources . . .