To be sure, manifold and successful attempts to found a greater political power were brought about by the advancing growth of industry and culture, as well as by the development of the citizen army of hoplites, which had a firm tactical structure and was well schooled in the art of war. In the Peloponnesus Sparta brought the whole south under the rule of its citizens and not only effected the union of almost the whole peninsula into a league, but established its right, as the first military power of Hellas, to leadership in all common affairs.

In middle Greece, Thebes succeeded in uniting Bœotia into a federal state, while its neighbour Athens, which had maintained the unity of the Attic district since the beginning of history, began to annex the neighbouring districts of Megara, Bœotia, and Eubœa, and laid the foundation of a colonial power, as Corinth had formerly done. In the north the Thessalians acquired leadership over all surrounding tribes. In the west, in Sicily, usurpers had founded larger monarchical unified states, especially in Syracuse and Agrigentum.

But all these combinations were after all only of very limited extent and by no means firmly united; on the contrary, the weaker communities felt even the loosest kind of federation, to say nothing of dependence, as an oppressive fetter which impaired the ideal of the individual destiny of the autonomous state, and which at least one party,—generally the one that happened to be out of power,—felt justified in bursting at the first opportunity.

However, as things lay, the nation found itself forced, with this sort of constitution, to take up the struggle for its political independence. The Greeks of Asia Minor, formerly subjects of the kings of Sardis, had become subjects of the Persian kingdom under Cyrus; the free Hellenes had the most varied relations with the latter, and more than once gave him occasion to intervene in their affairs. The Persian kingdom, which under Darius no longer attempted conquests that were not necessary for the maintenance of its own existence, took no advantage of these provocations until the revolt of the Greeks of Asia Minor, supported by Athens, made war inevitable.

After the first attempt had failed Xerxes repeated it on the greatest scale. Against the Hellenic nation, whose alien character was everywhere a hindrance in its path, the Orient arose in the east and the west for a decisive struggle; the Phœnician city of Carthage, the great sea power of the west, was in alliance with the Persian kingdom. Only the minority of the Hellenes joined in the defence; in the west the princes of Syracuse and Agrigentum, in the east Sparta and the Peloponnesian league, Athens, the cities of Eubœa and a few smaller powers. But in both fields of operation the Hellenes won a complete victory; the Carthaginians were defeated on the Himera, in the east Themistocles broke the base of the Persian position by destroying their sea power with the Athenian fleet that he had created, and on the battle-field of Platæa the Persian land forces were defeated by the superiority of the Greek armies of hoplites.

Thus the Hellenes had won the leading position in the world. For the moment there was no other power that could oppose them by land or sea; the Asiatic king never again ventured an attack on Greece. Her absolute military superiority was founded upon the national character, the energetic public spirit, the voluntary subordination to law and discipline and the capacity for conceiving and realising great political ideas. The Hellenes could gain and assert permanently the ascendency over the entire Mediterranean world, and impress upon it for all time the stamp of their nationality, provided only that they were united and saw the way to gather together all their resources into a single firmly knit great power.

But the Greeks were not able to meet this first and most urgent demand; though the days of particularism were irrevocably past, the idea which was so inseparably bound up with the very nature of Hellenism still exerted a powerful influence. As the individual communities were no longer able to maintain an independent existence, they gathered about the two powers that had gained the leadership, and each of which was striving for supremacy: the patriarchal military state of Sparta and the new progressive great power of Athens.

With the victory over the East it had been decided that the individuality of Hellenic culture, the intellectual liberty which gives free play to all vigorous powers in both material and intellectual life, had asserted itself; the future lay only along this way. Mighty was the advance that in all fields carried Greece along with gigantic strides; after only a few decades the time before the Persian wars seemed like a remote and long past antiquity.

But mighty as were the advancing strides of the nation in trade and industry, in wealth and all the luxury of civilisation, in art and science, all these attainments finally became factors of political disintegration. They furthered the unlimited development of individualism, which in custom and law and political life recognises no other rule than its own ego and its claims. The ideal world of the time of the sophists and the politics of an Alcibiades and a Lysander are the results of this development.

Athens perceived the political tasks that were set for the Hellenic people and ventured an attempt to perform them. They could be accomplished only by admitting the new ideas into the programme of democracy, by the foundation and extension of sea power, by an aggressive policy which aimed more and more at the subjection of the Greek world under the hegemony of one city. In consequence all opposing elements were forced under the banner of Sparta, which adopted the programme of conservatism and particularism, in order to strengthen its resistance, and restrict and, if possible, overcome its rival.