Athens passed a series of measures (the “Megarian decrees”) imposing an economic embargo on Megara for violations of sacred land. The religious aspect of the offense was reflected in the exclusions imposed: like murderers, the Megarians were banned from the Athenian marketplace and the harbours in the Athenian empire. But one should not doubt that Athens caused and intended to cause economic hardship as well or that the decrees were the first move in securing Megara as a military asset, a line of policy further pursued in the years 431 to 424. It should further be noted that the Black Sea, to which, as already mentioned, Pericles led a flamboyant expedition in the Great Gap period, was an area of colonial Megarian settlement; there too one can legitimately infer an Athenian desire to pressure Megara, albeit indirectly.
Reactions to all this, within the empire and outside it, are hard to gauge. Athens’ savage reduction of Samos, a member of the Delian League, in 440–439, did not stop Mytilene and most of Lesbos from appealing at some time in the prewar period to Sparta for encouragement in a revolt they were meditating. No encouragement was given: Sparta was standing by the Thirty Years’ Peace and should be given (a little) credit for doing so.
For the period from 433 to 411 a vastly more-detailed narrative is possible than theretofore, but the reader should be warned that this freak of scale is due to one man, Thucydides, who imposed his view of events on posterity. It would, however, be artificial to write as if the information for this unique period were no better than that available for any other.
The main precipitating causes of the war, thought of as a war between Athens and Sparta, actually concerned relations between Sparta’s allies (rather than Sparta itself) and other smaller states with Athenian connections. The two “causes” that occupy the relevant parts of Thucydides’ first, introductory book concern Corcyra and Potidaea. (Thucydides does not let his readers entirely lose sight of two other causes much discussed at the time—the Megarian decrees and the complaints of Aegina about its loss of autonomy. One 4th-century Athenian orator actually dropped a casual remark to the effect that “we went to war in 431 about Aegina.”) Corcyra (present-day Corfu), which had quarreled with Corinth over the Corcyran colony of Epidamnus on the coast of Illyria (a colony in which Corinth also had an interest), appealed to Athens.
Taking very seriously the western dimension to its foreign policy (it was about then that the alliances with Rhegium and Leontini were renewed), Athens voted at first for a purely defensive alliance and after a debate, fully recorded by Thucydides, sent a small peace-keeping force of 10 ships. That force, however, was trebled, as a nervous afterthought; no political background is given for the move, which, moreover, emerges only subsequently and in passing during the narrative of events concerning Corcyra itself. (This is a small illustration of the important point that Thucydides’ presentation unduly influenced modern views on the general issue of Athenian belligerence, as on so many other issues. A different narrative, by emphasizing the escalation of the Athenian commitment and making it the subject of another full debate, might have left a different impression. It is, however, hard to be sure if Thucydides’ postponement of the vital point was prompted by outright political bias in favour of Athens or if it was just a manifestation of a “Homeric” tendency to feed in information only at the point where it becomes most relevant). In fact, Corinthian and Athenian ships had already come to blows before the reinforcements arrived.
Then at Potidaea, a Corinthian colony, the Athenians demanded that the Corinthian magistrates be sent home. Potidaea revolted, and an unofficial Corinthian force went out to help. Potidaea was laid under siege by Athens. None of this yet amounted to war with the Peloponnesian League as a whole, but the temperature was as high as it could be, short of that. A congress of Spartan allies was convoked to discuss grievances against Athens, and the decision was taken for war.
The other Spartan ally seeking to involve Sparta in a private feud with an enemy was Thebes, whose attack on its neighbour Plataea (an Athenian ally) in time of peace was retrospectively recognized by Sparta as an act of war guilt. The Spartans should not have condoned it, nor should they have invaded Attica (despite the fact that the Athenians had placed a garrison in Plataea) so long as the Athenians were offering arbitration, as it seems they were. The initial phase, 431–425 Pericles
Athenian war strategy and the initial conduct of the war are presented by Thucydides very much in personal terms: the focus is on what Pericles, the dominant figure of this time, did or wanted. That method, like the Homeric emphasis on heroes, is to some extent literary spotlighting, for at no time was Pericles immune from criticism. In the 440s he had to deal with a major rival, Thucydides, son of Melesias (not the historian), who was ostracized in 443. Even after that, in the poorly documented 430s (before Aristophanes and Thucydides provide information about individual figures of second- or third-rate significance), there are suggestions of tension, such as a partial ban on comedy (with its potential for exposure) and indications in the sources that Cleon was really not a successor of Pericles at all but a highly critical contemporary. The reasons for Pericles’ ascendancy remain a secret, and that in itself makes it necessary to allow for a large element of “charismatic” leadership.
In the military sphere Thucydides is surely wrong to present Pericles as a one-man band. He says of Pericles that early in the war “the Athenians reproached him for not leading them out as their general should.” If this sentence had survived in isolation, one would hardly have guessed that Pericles was one of the college of 10, subject to control and threat of deposition by the Assembly (Pericles was indeed deposed temporarily toward the end of his life). On the whole, however, Thucydides minimizes the degree to which Athenian generals enjoyed executive latitude, particularly in wartime; it may be suggested that the reason for this was his own exile, imposed in 424 as a punishment for failing, as commander in the region, to relieve Amphipolis. This impressed him deeply—and unduly—with the impotence and vulnerability of generals other than Pericles.
The reproach of “not leading out the Athenians” provides useful insight into Periclean strategy, revealing it to have been largely reactive. Whereas the Spartans’ goal was to liberate Greece from tyranny, which required them to dismantle the Athenian empire, all the Athenians had to do was to avoid such demolition. In a way that suited neither side: initiative of the kind demanded from Sparta was in short supply there (though never entirely absent). For the Athenians’ part, the famously energetic and meddlesome population did not take kindly to the practical consequences of Periclean strategy that required it to evacuate Attica and move its population behind the fortified walls of Athens, to rely on accumulated capital reserves and on the fleet as an instrument to hold the empire firmly down, and to avoid adding to the empire during wartime. By these means the Athenians would eventually “win through” (the Greek word is neatly ambiguous as between victory and survival).
Actually the Athenian position was not and could not be so simple. For one, the agricultural evacuation of Attica was not as complete as it was to be after 413 when the Spartans occupied Decelea in northern Attica. Nor did Pericles altogether abandon Attica militarily: there were cavalry raids to harass the dispersed foot soldiers of the enemy and to keep up city morale. Holding the empire down and holding onto capital were potentially inconsistent aims in view of the great cost of siege warfare (there was no artillery before the 4th century to facilitate the taking of fortified cities by storm). The destruction of Samos had been expensive—a four-figure sum in talents—and the siege of Potidaea was to cost 2,000. Athens, even with coined reserves of 6,000 talents at the beginning of the war, could not afford many Potidaeas. Pericles can be criticized for not foreseeing this, with the evidence of Samos behind him. Sparta’s role