Euboian allies, the Thebans sought to detach Oropos from Athens and bring the city and its sanctuary back within the Boiotian fold. The city and its sanctuary were seized by the Boiotians, and the Athenian army sent to wrest it back was ill equipped to face the Thebans. The issue of possession of Oropos was turned over to arbitration.118 The most significant outcome of this embarrassing encounter was that the Arkadians were emboldened to seek an Athenian alliance, and the Athenians nervous enough to accept it, going to lengths to ensure that it would not violate the terms of their alliance with Sparta.119 It may also have been at this time that the Thebans voted to develop a navy by building a hundred triremes, with the stated aim of extending their hegemony on land to hegemony at sea in order to gain naval superiority over the Athenians.120 The process took several years, but this seems the most logical juncture for its inception.121 The Corinthians were deeply discomfited by the Arkadian-Athenian alliance and, after the brief tyranny of Timophanes at Corinth and the persistent threat from Argos, they went to Thebes seeking a general peace. The agreement that was reached under Persian and Theban auspices included Thebes, Corinth, Phleious, Argos, and probably Athens, but the Spartans refused to join, preferring instead to fight for Messene, which the peace treaty would have required that they surrender.122
Despite the strength of the Theban-led Boiotian koinon at this juncture—a navy in development, Persian support, and a general peace that excluded only Sparta—internal dissension wrought drastic and violent change in the region. A group of Theban aristocrats who had been expelled from their city sought to overthrow the democracy and enlisted the support of three hundred cavalry from Orchomenos. On the day of the planned attack, however, the instigators changed their minds and betrayed the plot to the boiotarchs, thus securing their own safety. The Orchomenian cavalry, by contrast, were arrested and brought before the popular assembly in Thebes, where the Thebans voted the most extreme measures imaginable: the cavalrymen guilty of conspiracy were to be executed; every remaining inhabitant of Orchomenos was to be sold into slavery; and the ancient city was to be razed to the ground.123 The decree was carried out quickly, and the city was only resettled two decades later. It is tempting to see this act of overwhelming violence perpetrated against a member city as part and parcel with the destructions of Plataia and Thespiai, and to see in all these episodes evidence for Theban aggression. Yet when seen from the standpoint of a federal state responding to secession attempts that would yield major breaches of security, all these cases take on a rather different perspective.
Meanwhile, Alexander of Pherai was still causing trouble in Thessaly, and despite Pelopidas’s narrow escape from the region in 367, he agreed to lead an army in 364 in response to a broad Thessalian appeal for help. Although Pelopidas died in the ensuing battle of Kynoskephaloi in 364, the Boiotians and their Thessalian allies enjoyed an overwhelming victory that led to the isolation of Alexander. He was compelled to surrender the other Thessalian cities he had subdued in war, and his rule was restricted to Pherai itself, under the further condition that he make himself an ally of the Boiotians. The Magnesians and Phthiotic Achaians were recognized as Boiotian allies, an alignment that had important ramifications almost a decade later.124
The initial decision to build a Boiotian fleet was mentioned above, and by 364 Epameinondas appears to have been in the Aegean working actively to further Boiotian maritime interests. The primary motive here was to weaken Athenian influence in the region.125 The alliance between Arkadia and Athens in 366, regardless of whether the Athenians partook of the Theban-sponsored peace of that year, was unsettling to the Boiotians, and Athenian support for the revolt of Ariobarzanes, the satrap of Hellespontine Phrygia, combined with a more aggressive approach to their relations with the Aegean states under the Athenian admiral Timotheos above all, meant that both the Thebans and the Persians were keen to change the situation. The Thebans remained the most loyal allies of Persia, and it was with Persian money that the fleet must have been funded. It is precisely in this period that we find the Thebans issuing electrum coinage, a remarkable (and ephemeral) phenomenon for fourth-century mainland Greece, and it can only be associated with the Persian-funded naval program.126 There is no doubt that the appearance of a Boiotian fleet of one hundred triremes on the Aegean in 364 was a remarkable novelty and may initially have been seen by disaffected Athenian allies as potentially capable of improving their situation.
The actual success of the plan was, however, more limited. When the decision was initially undertaken to build the fleet, the Boiotians planned to make overtures to Byzantion, Rhodes, and Chios.127 After sailing past an Athenian fleet unharassed, Epameinondas went to Byzantion, where he achieved the most signal success of the entire campaign. Although Justin, our only detailed source for the campaign, indicates that no formal alliance was made at Byzantion despite generally friendly feelings toward the Boiotians, we know that in this year a citizen of Byzantion was made proxenos of the Boiotians. By 362 Byzantion had broken away from the Athenian alliance and never returned to it, and in the 350s continued to have a close relationship with the Boiotians.128 The alignment was probably accomplished by Epameinondas in 364. Justin tells us that he had no success at Herakleia, Chios, or Rhodes, and no other source contradicts that report.129 But in general Epameinondas’s Aegean campaign must have been more complex than Justin reports. We know that the Athenian general Timotheos relieved a siege at Kyzikos, for which Epameinondas was probably responsible; it would have been a logical target if Byzantion was encouraging.130 A newly discovered proxeny decree of Knidos for Epameinondas (T8) reveals that he had friendly relations with that city and was given the right to sail in and out of its harbor freely. And an Athenian inscription for Keos reveals that the island broke away from the Second Athenian Confederacy, probably in 364/3, and was brought back in only with real difficulty. It is usually inferred, probably rightly, that Epameinondas had something to do with it: the Boiotians had, after all, benefited from the Euboean revolt of 366 and supported the activities of Themison, tyrant of Eretria, at the expense of Athens. Keos, virtually equidistant from the southern tips of Euboia and Attika, would have been an attractive ally if the island could be won.131 Although a careful study of the epigraphic evidence thus suggests a campaign far broader and more complex than literary sources let on, there is still no room to believe that Epameinondas achieved any lasting success in the Aegean in 364, and we never hear of renewed attempts by the Boiotians to exert any significant naval power.
Conflict in the Peloponnese, however, drew them back into action on land and presented the Thebans with another opportunity to show true leadership in Greece beyond the sheer military might they had demonstrated since Leuktra. In 363/2 they became involved in a war between the Arkadians and Elis that had broken out in 365 over the independent regional state of Triphylia and, later, over the use of sacred funds to pay the standing army of the Arkadians, the Eparitoi.132 Claiming that the Arkadians had violated their agreement with the Boiotians by resolving on war with Elis independently, the Boiotians staged a massive invasion of Arkadia with their Euboian and Thessalian allies.133 The defeat they suffered was totally unexpected. The battle of Mantineia in 362 resulted in enormous loss of life on both sides but, symptomatically for the mid-fourth century, had few decisive implications.134 Epameinondas himself was among those who died at Mantineia, and with him the Theban hegemony is conventionally thought to have ended.135 This is overly schematic: the Thebans continued to lead affairs in Boiotia and retained the allegiance of many of their allies. That the Athenians concluded an alliance with the Thebans’ Peloponnesian enemies after Mantineia comes as no surprise and should not be taken as an indication that Thebes was somehow finished. That the Spartans again remained outside the common peace that was concluded in 362/1, in order to fight for control over Messenia, further suggests that little had changed.136 It is easier to argue that the battle of Mantineia itself changed the sociopolitical landscape by forcing upon the Greeks a realization that even with massive bloodshed the differences that divided them could not be reconciled. If indeed they had that realization (and Xenophon certainly did), however, it affected old patterns of behavior little. The experiment with the limits of power held by a regional state like the Boiotian koinon, which was arguably the most innovative attempt to solve the ills that plagued fourth-century Greece, was still being conducted in Arkadia, but the strength of Boiotia and, in the north, of the Chalkideis, could not be
