History of the Peloponnesian War

Just before the battle joined, King Agis resolved upon the following manoeuvre. All armies are alike in this: on going into action they get forced out rather on their right wing, and one and the other overlap with this their adversary's left; because fear makes each man do his best to shelter his unarmed side with the shield of the man next him on the right, thinking that the closer the shields are locked together the better will he be protected. The man primarily responsible for this is the first upon the right wing, who is always striving to withdraw from the enemy his unarmed side; and the same apprehension makes the rest follow him.

On the present occasion the Mantineans reached with their wing far beyond the Sciritae, and the Lacedaemonians and Tegeans still farther beyond the Athenians, as their army was the largest.

Agis afraid of his left being surrounded, and thinking that the Mantineans outflanked it too far, ordered the Sciritae and Brasideans to move out from their place in the ranks and make the line even with the Mantineans, and told the Polemarchs Hipponoidas and Aristocles to fill up the gap thus formed, by throwing themselves into it with two companies taken from the right wing; thinking that his right would still be strong enough and to spare, and that the line fronting the Mantineans would gain in solidity.