Our major source for information on the officers of the Athenian army is the Aristotelian Athenian Constitution written in the 320s BC. Some argue that the text was not written by Aristotle and others claim that it is genuine. Such debates do not concern us here. There is enough evidence for earlier periods in the works of Herodotus, Thucydides, Xenophon, and other writers that we can corroborate the evidence of the Athenian Constitution (hereafter AC) or argue when things may have changed.
The AC tells us that all Athenian military officers were elected by a show of hands (43.1). The ten generals or strategoi were elected from the whole body of citizens rather than one from each tribe as had formerly been the case (AC 61.1) such as at Marathon (Plutarch Aristides 5). At Marathon, it seems as if the strategoi led the taxis of their particular tribe, and Callimachus, as polemarch, took the place of honour on the right wing (Herodotus 6.111). Below the strategos, ten taxiarchs were then elected, one from each tribe, followed by the elections of lochagoi by the members of each tribe (AC 61.3).
Several sections clearly reflect earlier practice at Athens, evidence corroborated by several fifth and fourth century BC sources. The system of ten , one per tribe, and, each commanded by a , is remarkably consistent. While we may not know how many there were in each Athenian , by the end of the fifth century BC they could act independently. Xenophon ( 1.2.3) has two operating separately from a in 409 BC. The number of could change in each situation: from these two to the full levy of all available men where every citizen was called upon (the ) such as at the battle of Delium in 424 BC (Thucydides 4.90.1). In all Athenian campaigns hoplites would be organized by tribe and so every Athenian army would presumably have ten of varying sizes each made up of several .
