History of the Peloponnesian War
Thucydides
Thucydides. The history of the Peloponnesian War, Volume 1-2. Dale, Henry, translator. London: Heinemann and Henry G. Bohn, 1851-1852.
and thus their orders, whatever they wish to be done, pass in the same manner, and quickly reach the troops; for pretty nearly all the army of the Lacedaemonians, a small portion excepted, are officers over officers; and to attend to what is going on is a duty incumbent on many.
On that occasion the Sciritae formed their left wing; who alone of the Lacedaemonians have always that post by themselves. Next to them were the soldiers who had served with Brasidas in Thrace, and the Neodamodes with them. Then came the Lacedaemonians themselves, with their lochi posted one after the other; by their side the Arcadians of Heraea; after them the Maenalians; and on the right wing the Tegeans, with a few of the Lacedaemonians holding the extreme position. Their cavalry was posted on each wing.
The Lacedaemonians, then, were drawn up in this way. On the side of their opponents, their right wing was occupied by the Mantineans, because the action was to be fought in their country; and by their side were the Arcadian allies. Then came the thousand picked men of the Argives, for whom the state had for a long time furnished at the public expense a course of training in military matters; next to them the other Argives; and after these, their allies the Cleonaeans and Orneans; then the Athenians, holding the extreme left, and their own cavalry with them.
Such was the order of battle and the preparation on both sides. The army of the Lacedaemonians appeared the larger of the two;
but as for stating any number, either of the several divisions on each side, or of their collective force, I could not do it with accuracy. For the number of the Lacedaemonians, on account of the secrecy of their government, was not known; and that of the others, in consequence of men's natural tendency to boasting with regard to their own numbers, was regarded with distrust.