Not everything in politics and war is necessity, interest or the thrill of doing down opponents. In agonistic times there can also be a restlessness, a diffuse and unfocused disposition to find something to act against. So it can appear to have been with the Athenians in the sixteenth year of this conflict. Frustrated in Greece itself, they were more strongly inclined than they had been ‘to sail to Sicily and subjugate it if they could’. Few in Athens, Thucydides says, had much sense of the island or realised that if they were to try to conquer it they would be ‘taking on a war on almost the same scale as that against the Peloponnesians’ (6.1.1). He knew himself that Syracuse was as large as Athens (7.28.30). But even he may not have appreciated that Sicily contained a fifth of the 3 million or so Greeks against no more than a further fifth in Athens’ dominions to the east and a tenth in Attica, or that Sicily had twice as much land under cultivation as the whole of the rest of ‘Hellas’. One can nevertheless believe him when he says that those who voted for another expedition to Sicily did not see themselves to be starting a large war; suggests, without quite saying so, that they would not have seen themselves to be starting a war at all; suggests that most of them did not know quite what they had in mind. Apart from Nicias and perhaps a few others, ‘Athenians’ may in some sense have wanted to subjugate Sicily. But it would be too strong to say that they were determined to do so and too strong to say that they weren't. They were, one might say, in a mood to see.

Thomas Macaulay often read while he walked. ‘Walked out over Westminster Bridge’, he wrote in his journal for 24 November 1848, ‘and back by the Hungerford Bridge. Read the first book of Thucydides – excellent. I never liked him so much’; 26 November, ‘after breakfast – read Thucydides during some time. Finished the third book’; 1 December, ‘began the sixth book of Thucydides – very good’; 2 December, ‘walked home and began the seventh book’; 3 December, ‘finished the seventh book’; 4 December, ‘staid at home all day – a miserable rainy day – making corrections for the 2nd edition [of the History of England]. Then read the eighth book of Thucydides – not every word – but particularly the account of the Athenian revolutions.’ ‘On the whole’, Macaulay reflected later that afternoon, ‘Thucydides is the first of historians. What is good in him is better than anything that can be found elsewhere. But his dry parts are dreadfully dry; and his arrangement is bad.’

Few can have read so much difficult Greek prose so quickly; the text in a modern English translation can run to nearly 600 pages. Few certainly will have read any of it while walking through the stink and noise of London in the 1840s or, as Macaulay also had, while taking a shave. But many have read the first seven of the eight books into which the text has been divided with comparable enthusiasm. They too are drawn into the story of men in what Thucydides called ‘the war of the Peloponnesians and Athenians’, ‘dealing sensibly, foolishly, sometimes catastrophically, sometimes nobly’ as Bernard Williams put it ‘with a world that is only partly intelligible to human agency’. But many have shared Macaulay's dismay in reading on. They too have found the narrative in book 8, up to what he calls the ‘Athenian revolutions’ of 411, to be ‘dull and spiritless’ and lacking in drama, an aimless sequence in which he seems ‘to grope his way like a man without a clue’; ‘a series of not even well-connected outlines’; running on ‘flat and monotonous, offering no outstanding feature as a starting point for analysis’; ‘a bald record of quarrels, back-stabbing and inconclusive struggles’ which after the account of the ‘revolution’ in Athens (more exactly a coup) ‘breaks off in mid-stream’ and offers no end; a sequence that is simply stuffed with too many facts.

The asterisked sections in this synopsis are those I do not discuss in any detail. Although not central to my argument, all contribute to Thucydides' narrative and some are of considerable historical, military and literary interest.

Book 1

1. Introduction [1.1–23.3]

2. Reasons for writing [1.1]

3. Early history of Greece [1.2–19]

4. Aims and methods [1.20–2]

5. Importance of this war [1.23.1–3]

6. Background to the war [1.23.4–46]

7. Causes of the war [1.23.4–6]

8. Epidamnos and Corcyra [1.24–55]

9. Potidaea [1.56–66]

10. First meeting of Peloponnesian league [1.67–88]

11. ‘Fifty years’ of Athenian power [1.89–118]

12. Second meeting of Peloponnesian league [1.119–25]

13. Spartan ultimatum and Pericles’ response [1.139–46]

Book 2

1. First year of the war, 431–430 First year of the war, 431–430

2. Outbreak of war [2.1]

3. Thebans attack Plataea [2.2–6]

4. Preparations and alliances on both sides [2.7–17]

5. Peloponnesians invade Attica [2.18–32]

6. * Corinthians active in west [2.33]

7. Pericles’ funeral speech at Athens [2.34–2.47.1]

8. Second year of the war, 430–429 [2.47.2–70]

9. Peloponnesians invade Attica [2.47.2]

10. Plague at Athens [2.47.3–54]

11. Spartan campaigns and Pericles’ response [2.55–64]

12. Thucydides’ assessment of Pericles and Athens’ eventual defeat [2.65]

It would be striking indeed if Thucydides is right to say that the whole of Greece ‘experienced an immediate surge of elation’ after Athens’ defeat in Sicily: that even ‘those who were aligned with neither side were thinking that even if no one invited them to join in they should no longer stand aside from the war but should of their own accord move to attack the Athenians, each of them reasoning that the Athenians would have done the same to them had they met with success in Sicily; and that they calculated that the rest of the war would be short-lived and that it would be a fine thing to have played some part in it’. It would suggest that the Hellenes felt themselves to be one. But it is easy to believe in the ‘eagerness’ of Sparta's allies to be released from the ‘great hardships’ of war and that ‘most important of all, the subjects of Athens were now ready to revolt from her, even beyond their means to do so, because they were judging the situation in a mood of high emotion and could see no case for believing the Athenians would survive through the following summer’ (8.2.1–2). All sides, says Thucydides, were preparing for conflict ‘as though they were only now beginning it’ (8.5.1). The ‘first war’ as he had thought of it had ended in 421 (5.24.2). This was in effect the start of ‘another’ (7.28.3).

It is not always easy to see what the protagonists’ ambitions might have been in the previous eighteen years, not least because they did not always seem themselves to be sure. But now they were. The Athenians wanted to save themselves and what they could of their dominion, and the Peloponnesians and disaffected parties in Athens’ subject states wanted to end it. But the subject states could not be sure of succeeding alone and neither of the two leading powers was confident of achieving what it wanted to with its own resources. Each accordingly sought support from Persian satraps in Anatolia, who were themselves being pressed to raise revenues from the Greek settlements that had been ceded to them in 449. The politics therefore were simpler than before.

Thucydides’ account of ‘the war of the Peloponnesians and the Athenians, how they waged it against each other’ between 431 and 411 bc, has never been easy to read. At the end of the first century bc, in the earliest comments on the text that survive, Dionysius of Halicarnassus said that those who could master its Greek ‘are easily counted’. Lorenzo Valla, presenting his translation into Latin to the Pope in 1452, explained that the eight books into which it had come to be divided, ‘these eight towns, just so that you know this, my Imperator, for perhaps you know not what sort of towns you ordered me to take, are situated in the loftiest regions, in craggy mountains, and defy missiles, battering rams, ladders, trenches and the mines of sappers’. Thucydides knew, and made no apology. ‘The absence of the element of fable in my work may make it seem less easy on the ear, but it will have served its purpose well enough if it is judged useful by those who want to have a clear view of what happened in the past and what – the human condition being what it is – can be expected to happen again some time in the future in similar or much the same ways. It is composed to be a possession for all time and not just a performance-piece for the moment.’

Yet it stops suddenly, in mid-sentence, seven years before the war had ended (though there are insertions that Thucydides could only have made, if it was he who made them, when it had). And its style apart, the text is unusual. No one had written as he did, and no one was to do so in the same way again. It is more than a chronicle, recalls epic, has elements of tragedy and is intended to be of use; but Thucydides’ few conclusions do not convince and he does not say what its use might be. It falls across all our genres and is diminished when assigned to any.

‘Thucydides of Athens wrote the war’ (1.1.1). Many translators have said that he wrote the history of the war. Others could say that he wrote a history, one of the many that could have been written. But both, the question of history aside, would understate him. The verb he uses, sungraphein, with which he also often signs off his account of a year, was unusual and in a world in which prose was still rare, ambiguous. Literally ‘to depict together’ and by extension ‘to bring together in writing’, it can allow us to read him both to say that he wrote up the information he had and constructed the war to make it the one we should know. He may mean both.

Events, erga, things done (1.22.2), were as they were; if they happened they happened and had to be recovered. There is no reason to doubt that Thucydides investigated the reports he received ‘with the utmost concern for accuracy’ and was in reporting as truthful as he could manage. Likewise with the speeches, even if he had more often than not to resort to imagining what the speaker in question would ‘most appropriately’ have said in the circumstances in which he found himself. And in writing all this down he sought the authority that writing gave. The most extreme contrast would have been with the vagaries of oral exchange in the conditions of internal war, where ‘simplicity’ of spirit – as Hobbes translates it, ‘sincerity’ – ‘was laughed to scorn and vanished’ (3.83.1). ‘Men assumed the right to reverse the usual values in the application of words to actions’ (3.82.4), and nothing said could be trusted. The comparison would have been with the aspiration of the Athenian general Nicias. Wanting to be sure he could convey the predicament he found himself in in Sicily in 414 and fearing that a messenger's oral account ‘would fail to report the true facts, whether through lack of ability in speaking or failure of memory or a wish to indulge mass opinion’, Nicias sent a letter so that those in Athens ‘should deliberate with a view to the truth of the matter’ (7.8.2).

Thucydides allows one to think that Sparta and Athens found themselves at war in spite of themselves. Or more exactly, that each found itself no longer at peace. A majority at Sparta had been hustled into deciding that the treaty of 446–445 had been broken. Some wanted still to delay, but most had been incited to believe that they had been humiliated enough. Some in Athens wanted to come to an understanding, but Pericles had prevailed. He believed that war was unavoidable if the city was to retain its dominion and prosperity and thereby assure its future glory, but that this was not the moment to fight it. Megara could be harassed, there could be raids along the Peloponnesian coast, and Potidaea had to be brought back, but nothing else was immediately feasible. The Peloponnesians should accordingly be allowed to fail, and in Attica they did. They invaded for a second time in 430, returned in 428 and 427, were deterred by an earthquake in 426 and in 425 stayed for just fifteen days before leaving to deal with a threat in the Peloponnese itself. Thucydides does not say as much but his narrative makes it clear: the Spartans could not see how otherwise to take the war to the Athenians and the Athenians could not see how to take the war to the Spartans at all.