After Leuctra there was a second peace of 371, this time at Athens. It is disputed whether Sparta participated, but it is certain that the Thebans were again excluded. It is also certain that the peace included undertakings to accept “the decrees of the Athenian allies”—a possible reference to the Second Athenian Confederacy and in any case a further strengthening of Athens’s position.
Sparta’s position, by contrast, now began visibly to crumble. In Arcadia, not merely did the Mantineans organize themselves into a polis once more, but Arcadia as a whole became a federal state on the initiative of a Mantinean called Lycomedes. (The capital was to be at Megalopolis, the “Great City,” a new foundation made necessary by the ancient rivalry between Tegea and Mantinea.) Both these movements were obviously anti-Spartan, and the Arcadian federation badly needed military support from some powerful quarter. The Arcadians found it at Thebes, after being rejected by Athens (if Athens had responded positively to this appeal, major Peloponnesian developments of the 360s might never have taken place).
Federal Arcadia was in origin a local growth, but there is no doubt that Theban support was crucial for its subsequent success. Theban promotion of federalism there and in central Greece is a notable political contribution, for which the evidence is largely inscriptional. Federations are attested in this decade not just in Arcadia but north of the Gulf of Corinth, in Aetolia, an ally of Thebes since 370, and in western Locris. There was also an intriguing Boeotian federal organization of Aegean states in the 350s, complete with synedrion on the Athenian model. All these federations arguably betray the influence of the Thebans, who evidently sought to export the federal principle long familiar in Boeotia itself. On a skeptical view, however, the development was a natural one and merely approximately simultaneous with the period of maximum Theban power.
In 370–369 Epaminondas invaded the Peloponnese (the first of several such invasions) and weakened Sparta irreparably by refounding Messene as a physical and political polis; the “state-of-the-art” fortifications of 4th-century Messene, an artillery-conscious circuit, stretched for nearly four miles over Mount Ithome. They are the best preserved in mainland Greece except perhaps for Aegosthena at the east end of the Gulf of Corinth; in Anatolia only Heraclea on Latmus, in Mausolus’s Caria, is comparable. The loss of Messene crippled Sparta economically; in particular, Sparta no longer had a helot population to provide the economic surplus necessary for its military life-style. The combined impact of Leuctra, Megalopolis, and Messene was, however, not immediately obvious; in the “Tearless Battle” of 368, Sparta still managed to win a victory over a force of Arcadians. But Sparta was no longer a leading power. Athens and Thebes
In the 360s the main focus of Greek history shifted from Sparta to the struggle between Athens and Thebes. Neither power was really strong enough to impose a definitive solution, nor were outside forces available to give either side a decisive margin of superiority in the way that Persia had allowed Sparta to prevail in the Peloponnesian War. The 360s were a period of satrapal revolts in the western half of Artaxerxes’ empire, and the subjugation of Egypt continued to elude him. In effect, though there also was some Persian-sponsored inter-Greek diplomacy in this decade, there was even less threat of force behind it than usual (the King’s Peace of the 380s and that of the 370s had not been backed up by Persian men or ships). Dionysius I had added his weight on the Spartan side in 386, and his troops were found operating against Thebes as late as the early 360s. After his death, however, Sicily was not a serious factor in mainland Greek politics. Dionysius’s son Dionysius II did send help to Sparta, enabling it to recover control over some formerly subject communities in 365, but that was about the limit of his interference. Dionysius II ruled precariously in Syracuse and southern Italy; he recovered Syracuse only to be finally driven to exile in Corinth by the Corinthian Timoleon in the 340s. The mid-century period of Syracusan history is of interest because of Plato’s involvement in the politics of the tyranny. Dion, a relative of the older Dionysius by marriage, invited Plato to Syracuse in 367 to tutor Dionysius II in science and philosophy and generally to educate him to become a constitutional king; the visit, however, was not a success.
In central and northern Greece, the energetic rule of Jason (which might have given a push to the plans of his Theban allies) had ended abruptly in 370, and his eventual aims remained and remain an enigma. Macedon was the power of the future, but that was far from obvious in the 360s. After the death of Amyntas in 370, Macedon relapsed into a period of short unstable reigns, as in the 390s. Thus, neither Thessaly nor Macedon was in a position to tilt the balance of power.
Thessaly and Macedon, however, were valuable prizes. Thessaly was not only enormously fertile but also had good harbours and religious influence in the Delphic amphictyony. Macedon had ship-building timber and great natural resources (though few outlets to the sea because Greek colonial poleis stood in the way). Sparta could no longer compete for these assets, but Athens and Thebes could. Not long after the peace of 371, Athens restated an old claim to Amphipolis and added a claim to the Chersonese; in 368 it sent its general Iphicrates to Amphipolis. Thebes reacted to the Athenian claims by sending its other great man of the 4th century, Pelopidas, to Thessaly and Macedon. Theban activity in these areas did not add up to much in the end (one incidental result was that the young Philip, son of Amyntas, spent a period in Thebes as a hostage. The relevance, for Philip’s subsequent army reforms, of his exposure to the methods of the first military state in Greece has often been noted). It did, however, show the Greek world the scale of Theban ambitions.
By 367, affairs in Thessaly and Arcadia were temporarily stalemated, and a peace conference was held at Susa, inside the Persian empire. Pelopidas asked that Sparta be made to give up Messenia formally and (more important, in view of Sparta’s relative impotence at this time) that Athens be requested to give up its fleet. When these proposals inevitably failed, Thebes seized the valuable border territory of Oropus, and Athens was after all obliged to accept what was probably a King’s Peace (366). There was, however, no question of Athens dismantling its navy; on the contrary, its claims to the Chersonese (reachable only by sea) were recognized in exchange, it seems, for acceptance of Theban leadership of Boeotia, including Oropus.
Athens’s pursuit of essentially private Athenian aims, such as control of Amphipolis and the Chersonese, cannot have pleased its allies in the confederacy. It was costly, and it was unsuccessful. (Securing the recognition of Athenian claims in theory was not the same thing as making good those claims in practice.) On the other hand, Athens, shortly after the peace of 366, did send help—a force under Timotheus—to a rebel satrap, Ariobarzanes, in the eastern Aegean; that act showed a perhaps encouraging willingness to defend Greek interests against Persia, especially since Timotheus ejected a Persian garrison he found installed on Samos. The Persian garrison was a violation of Persia’s side of the original King’s Peace. It may seem surprising that Athens should act against Persia so soon if the peace of 366 was really a King’s Peace, but the risk of reprisals just then was slight. In any case, Timotheus’s somewhat contradictory instructions were to keep to the King’s Peace while also helping Ariobarzanes.