To persuade your enemy to (retreat) before the fight is to defeat them even before the battle begins. An enemy made ally is no longer an enemy.
Sun TzuShould the enemy strengthen his van, he will weaken his rear; should he strengthen his rear, he will weaken his van; should he strengthen his left, he will weaken his right; should he strengthen his right, he will weaken his left. If he sends reinforcements everywhere, he will everywhere be weak.
Sun Tzu