We may thus understand why the offer of Olynthus was gladly welcomed by the Macedonian maritime cities. They were the first who fraternized as voluntary partners in the confederacy; which the Olynthians, having established this basis, proceeded to enlarge farther, by making the like liberal propositions to the Greek cities in their neighborhood. Several of these latter joined voluntarily; others were afraid to refuse; insomuch that the confederacy came to include a considerable number of Greeks,—especially, Potidæa, situated on the Isthmus of Pallênê, and commanding the road of communication between the cities within Pallênê and the continent. The Olynthians carried out with scrupulous sincerity their professed principles of equal and intimate partnership, avoiding all encroachment or offensive preëminence in favor of their own city. But in spite of this liberal procedure, they found among their Grecian neighbors obstructions which they had not experienced from the Macedonian. Each of the Grecian cities had been accustomed to its own town-autonomy and separate citizenship, with its peculiar laws and customs. All of them were attached to this kind of distinct political life, by one of the most tenacious and universal instincts of the Greek mind; all of them would renounce it with reluctance, even on consenting to enter the Olynthian confederacy, with its generous promise, its enlarged security, and its manifest advantages; and there were even some who, disdaining every prospective consideration, refused to change their condition at all except at the point of the sword. Among these last were Akanthus and Apollonia, the largest cities (next to Olynthus) in the Chalkidic peninsula, and, therefore, the least unable to stand alone. To these the Olynthians did not make application, until they had already attracted within their confederacy a considerable number of other Grecian as well as Macedonian cities. They then invited Akanthus and Apollonia to come in, upon the same terms of equal union and fellow-citizenship. The proposition being declined, they sent a second message intimating that, unless it were accepted within a certain time, they would enforce it by compulsory measures. So powerful already was the military force of the Olynthian confederacy, that Akanthus and Apollonia, incompetent to resist without foreign aid, despatched envoys to Sparta to set forth the position of affairs in the Chalkidic peninsula, and to solicit intervention against Olynthus.