Xenophon Hellenica 4.2.18

[18]
  This, then, was the force on either side. Now the Boeotians, so long as they occupied the left wing, ¹ were not in the least eager to join battle; but when ² the Athenians took position opposite the Lacedaemonians, and the Boeotians themselves got the right wing and were stationed opposite the Achaeans, they immediately said that the sacrifices were favourable and gave the order to make ready, saying that there would be a battle. And in the first place, disregarding the sixteen-rank formation, ³ they made their phalanx exceedingly deep, and, besides, they also veered to the right in leading the advance, in order to outflank the enemy with their wing; and the Athenians, in order not to be detached from the rest of the line, followed them towards the right, although they knew that there was danger of their being surrounded.