In the negotiations which were concluded by the Peace of Philocrates, Philip hoped to gain control of the Greek states so that he could invade Persia with his own kingdom secure from invasion by powerful enemies in his rear. Elimination of the Thebans as a leading state was an essential step in his plan, because he could foresee that the only combination sufficiently strong to thwart him would be Athens and Thebes. For this reason he insisted on an alliance with the Athenians as a necessary condition for the peace: he hoped that on the basis of this alliance the Athenians would send hoplites to Thermopylae who would aid him both in the suppression of his Theban allies and in the expulsion of Phalaecus and his mercenaries from the forts. He expected that, when the Thebans learned that the tyrant and his troops were to be punished severely and the Phocian people treated leniently, the Thebans would be provoked into attacking him and the Athenians would come to his aid by taking them in the rear.