History of the Peloponnesian War

But while they were still closing, King Agis resolved to make the following manoeuvre. All armies are apt, on coming together, to thrust out their right wing too much; and both sides extend with their right beyond their opponents' left wing, because in their fear each man brings his uncovered side as close as possible to the shield of the man stationed on his right, thinking that the closer the shields are locked together the better is the protection. And it is the first man on the right wing who is primarily responsible for this, since he always wants to withdraw from the enemy his own uncovered side, and the rest, from a like fear, follow his example.

And so on this occasion the Mantineans extended with their right wing far beyond the Sciritae; and the Lacedaemonians and Tegeates further still beyond the Athenians, inasmuch as their army was larger.

So Agis, in fear that his left might be encircled, and thinking that the Mantineans were extending too far beyond it, gave orders to the Sciritae and the soldiers of Brasidas to move out, away from his main body, and make the line equal to that of the Mantineans; then he directed two polemarchs, Hipponoïdas and Aristocles, to cross over with two companies from the right wing, throw themselves in and fill up the gap thus created, thinking that his own right wing would still have more than enough men, and that the line opposed to the Mantineans would be strengthened.