For if you send a marauding expedition, he will stand on the defensive until he has made himself master of Olynthus , and then he will easily march to the relief of his own territory; or if you confine yourselves to helping Olynthus , he will know that his base is secure and will give close and undivided attention to his operations, until at last he overcomes the resistance of the besieged. Our expedition, you see, must be on a large scale and twofold.