The invasion army of 334 B.C.

In the spring of 334 Alexander's army was assembled at Amphipolis and a smaller expeditionary force was already operating in Asia Minor. The total number of troops is difficult to estimate because of the diversity of figures given in the sources, ranging from a maximum of 43,000 foot and 5,500 horse to a minimum of 30,000 foot and 4,000 horse. Some of the discrepancy may be explained by some authorities including the advance force in their total and others omitting it; but the inconsistencies run deep and cannot all be resolved on that hypothesis. Fortunately the size and composition of the Macedonian contingents is not seriously in doubt. Alexander took with him 12,000 infantry and left the same number with Antipater, his regent in Macedonia (Diod. XVII. 17.4, 5). There was also a body of Macedonians already serving in Asia (Diod. XVII.7.10), several thousands strong. After Alexander crossed the Hellespont the total of his Macedonian infantry was around 15,000. The majority were brigaded in six phalanx divisions (which Arrian usually terms taxeis) and had the collective title of Foot Companions (pezhetairoi). Three of these divisions at least were recruited from the old principalities of Upper Macedonia and are termed asthetairoi, a most mysterious appellation which has yet to be explained satisfactorily.2 The other taxeisdo not apparently bear any distinctive nomenclature, but they may well have been recruited on a similar regional basis (cf. Arr. III. 16.11). The other major component of the Macedonian infantry was the corps of hypaspists.