response to the Persian threat, the Athenians developed the largest navy in the Greek world. Even more importantly, the Persian Wars instilled into the Athenians the mindset that not only could they protect their fellow Greeks from any possible Persian repercussions, but that as the saviors of Greece they were entitled to exercise hegemony over them (Aesch. Pers. 233–234; Hdt. 7.139; Thuc. 1.73–75.1, 5.89, 6.83.2). The foundation of the Delian League (so named after the organization’s headquarters on the island of Delos, site of an important pan-Ionian sanctuary) in 478/477 afforded the Athenians leadership over willing allies.2 Athenian control over the allied naval forces as well as the annual tribute of those allies who did not contribute ships (Thuc. 1.96.2) soon gave them the ability to rival the Spartans’ military dominance in Greece through leadership of the Peloponnesian League. As Thucydides observes (1.18.2–3), not long after the Persian Wars the Greek world became divided between two great powers, Athens on the sea and Sparta on land, each heading a coalition of allies. The military polarization between the two soon shaded into the realm of ideology, as the Spartans tended to favor oligarchic governments and the Athenians democratic ones. When the uneasy alliance forged during the Persian Wars began to fray, the stage was set for a major confrontation between Athens and Sparta, each of which now possessed the manpower and the resources to wage extensive year-round campaigns far beyond their borders throughout the Greek world.
The “First Peloponnesian War” (460–446/445)
Although the Spartans at first acquiesced in the Athenian leadership of a maritime naval alliance,3 it soon became apparent that the Athenians had their own increasingly imperialistic interests in mind at least as much as action against the Persians, the ostensible purpose of the Delian League.4 According to Thucydides, our main source for the period between the Persian Wars and the Peloponnesian War (the so-called Pentekontaetia or “Fifty Years”), the early years of the Delian League were marked not only by naval campaigns against Persia, but also by the increasingly heavy-handed Athenian treatment of their allies, including the forcible subjugation of members of the League who attempted to secede (Thuc. 1.98–100). Thucydides’ terse narrative is tendentious, however, and deliberately shaped to support his contention that the “truest cause” (as he put it) of the Peloponnesian War was the growth of Athenian power and the fear it engendered in the Spartans (1.23.6). For what it is worth, the Spartans also experienced difficulty in maintaining control over their Peloponnesian allies in the decades following the Persian Wars.5 Nevertheless, despite the appearance of cracks in the truce between Sparta and Athens (most notably the Spartan opposition to the Athenian rebuilding of their city walls and the alleged secret promise of the Spartans to support the Thasians in their revolt by invading Attica),6 open hostility did not break out until the Spartans dismissed the Athenian commander Cimon and his troops who had come to assist them in suppressing the helot revolt at Mount Ithome (Thuc. 1.101–102).
This unceremonious dismissal had far-reaching consequences, for the Athenians renounced their existing alliance with the Spartans, and energetically proceeded to make alliances with Sparta’s traditional enemy of Argos as well as Thessaly (Thuc. 1.102.3). They also accepted an alliance in 461 with the Megarians, erstwhile members of the Peloponnesian League who were getting the worst of an ongoing border dispute with their Corinthian neighbors (Thuc. 1.103.4). Megara’s strategic location on the narrow isthmus joining the Peloponnese to central Greece was not lost on the Athenians, who immediately connected Megara and its port of Nisaea on the Saronic Gulf with protective walls, which they garrisoned with their own troops (Thuc. 1.103.4). Not only was this overtly expansionist activity around the isthmus threatening to the Corinthians in particular (Thucydides 1.103.4 influentially identifies it as the “original cause of the extreme hatred” of Corinth for Athens7) but the Athenian control of Megara prevented the Spartans from leading troops out of the Peloponnese by land into central Greece.8 This blatant Athenian attempt to extend their sphere of influence provoked a series of open conflicts with the Spartans and their Peloponnesian allies (especially Corinth), conventionally but somewhat misleadingly known as the First Peloponnesian War (Lewis 1997, 72).
In the opening engagement, the Athenians attempted to counter Corinthian ambitions in the eastern Peloponnese by attacking the port town of Halieis on the Argolic gulf (possibly on behalf of their new ally Argos, but almost certainly also to consolidate their own control of the Saronic Gulf),9 where they were defeated in a land battle by the Corinthians, Epidaurians, and Sicyonians (Thuc. 1.105.1, with SEG 31.369). Despite this inauspicious beginning, the Athenians defeated the Peloponnesians soon afterward in a sea battle off the small island of Cecryphalea just west of Aegina (Thuc. 1.105.1) and followed up this victory with a decisive defeat of the powerful Aeginetan fleet (along with their Peloponnesian allies), which enabled them to lay siege to Aegina (Thuc. 1.105.2), the large island that was their longtime rival in the Saronic Gulf. The Corinthians attempted to aid the Aeginetans by sending forces to attack Megara, assuming that with so many troops committed overseas in the Egyptian expedition the Athenians would be forced to withdraw from Aegina (Thuc. 1.105.3). The Athenian general Myronides defied expectations by leading the reserve troops (that is, those considered too young or too old for active duty) to Megara, where they defeated the Corinthians first by a narrow margin and then more decisively in a second battle culminating in the massacre of their retreating foes (described vividly by Thucydides 1.106.1–2).10 Despite their initial success, the Athenians were sufficiently nervous of a possible Peloponnesian invasion by land that they began to construct the Long Walls linking the city to the Piraeus in order to ensure that Athens could not be cut off from the sea (Thuc. 1.107.1).
It is at this point that Thucydides records the Spartans as openly entering the conflict for the first time,11 sending an army to liberate their mother city of Doris in central Greece from the Phocians (Thuc. 1.107.2).12 Although Thucydides (1.107.3) tells us that after their expulsion of the Phocians the Spartan forces were prevented from returning home by land and by sea (thanks to Athenian control of the isthmus and the Corinthian Gulf) and therefore decided to cross into Boeotia instead, it is far more likely that the Spartans’ actual intention was to build up the Theban army (in return for support of Theban hegemony over Boeotia) as an effective force against Athens beyond the isthmus.13 The Athenians, wary of the danger presented by a Spartan–Boeotian rapprochement (particularly in light of overtures to the Peloponnesians by political opponents of the democracy in Athens, if Thucydides 1.107.4–6 can be believed), sent a large army to fight at Tanagra, but were no match for the Spartans on land (Thuc. 1.108.1). Two months later, the Athenians under Myronides retaliated by marching north and defeating the Boeotian army at Oenophyta, which left them in control of much of central Greece (Thuc. 1.108.2),14 and soon afterward of the Saronic Gulf as well, through their reduction of Aegina (Thuc. 1.108.4).
This aggressive policy of expansion culminating in the Athenian acquisition of a land empire could not be sustained indefinitely, particularly with the ongoing large-scale naval campaigns against the Persians in the eastern Mediterranean, and the Athenians soon suffered a series of reverses (Thuc. 1.109–111), prompting them to sign a five-year truce with the Peloponnesians (Thuc. 1.112.1).15 During the period of the truce, the only recorded conflict between the Spartans and the Athenians occurred indirectly over control of Delphi.16 Upon its conclusion, the Boeotians lost no time in exploiting Athenian vulnerability by revolting, and an Athenian army was defeated at Coronea, forcing the Athenians to withdraw from all of Boeotia (Thuc. 1.113). The uprising in Boeotia was soon followed by the revolts of both Euboea and Megara, and the Spartan invasion of Attica (Thuc. 1.114). The Athenians had no choice but to give up any formal claims to a land empire (not only central Greece, but all of their land outposts in the Peloponnese) in the Thirty Years’ Peace they signed with Sparta in 446/445 (Thuc. 1.115.1),17 the terms of which cemented the division of the Greek world into two great power blocs, Athens exercising hegemony by sea and Sparta by land.18
The Peloponnesian War (431–404)
Despite the mutual recognition of separate spheres of influence, the Thirty
