The Battles at Cynossema, Abydos, and Cyzicus had netted Athens welcome victories, but control of the straits was far from secure. The Spartans still held Sestos, Chalcedon, and Byzantium. Though ultimately the outcome of the war would be decided in the Hellespont, distractions often kept both sides occupied elsewhere; and of course the Athenians were divided about the matter of Alcibiades, whose citizenship had not yet been returned to him even though the “government in exile” at Samos had elected him general. The two coastal satraps, Tissaphernes and Pharnabazus, continued to flex their muscles, enjoying the power they wielded, until their game was brought to an abrupt end by Darius’s decision to make his younger son Cyrus satrap of such a wide area as to eclipse Tissaphernes entirely. Once again, as had been the case with Brasidas, the Spartans found a charismatic military commander. At a time when both sides were in desperate need of funds to pay their men, the navarch Lysander not only showed boundless energy but struck up a lucrative friendship with the Persian prince. But even this dangerous alliance need not have presented such a threat to the Athenians’ fortunes had it not been for unpredictable developments in Ionian waters.
In 409 the Athenians sent Thrasyllus out at the head of a force of fifty triremes, with 5,000 of his men equipped as peltasts and 100 cavalry; in total, he had 11,000 men. He was to see what he could accomplish in Ionia before moving north to join with Alcibiades in the Hellespont. After some minor successes, however, he was defeated at Ephesus, where he faced not only the Ephesians and their Sicilian allies but also the cavalry of Tissaphernes, who had gotten wind of his impending attack, and when the fighting ended, the Athenians had lost at least 300 men.
Retreating northward after burying their dead, they caught sight of the Syracusan ships retreating from Ephesus and managed to capture four of them. Thrasyllus sent all the crews back to Athens, where—for poetic justice—they were shut up in the stone quarries at the Piraeus. The Athenians were greatly disappointed when the captives managed to dig their way out at night not long afterward. One prisoner, however, was dispatched on the spot. Alcibiades’ cousin, also named Alcibiades, of the deme of Phegous, who was already under sentence of death for profaning the mysteries in 415 and had thus shared the exile of his more famous relation, had been fighting along with the Syracusans, and Thrasyllus ordered him stoned to death as a traitor and enemy combatant—an unusual punishment in Athens but not unheard of in cases of treason during wartime.
Thrasyllus and his men then proceeded northward to join Alcibiades’ troops at Lampsacus in the narrow Hellespontine straits that divided the Aegean from the Propontis (the modern Sea of Marmara). There the combined forces set about dislodging the Peloponnesians from several key strongholds. In the combat in the Hellespont, both sides would have to exercise determination and vigilance and also think along innovative lines, and there would be no room for error. During this fighting season, it was the Athenians who showed imagination and the Spartans who made a crucial error—more specifically, perhaps, Alcibiades who showed imagination and Clearchus who made the crucial error.
The Athenians’ siege of Chalcedon opposite Byzantium at first proceeded along traditional lines, as Athenian soldiers enclosed the rebellious city by a wooden wall and Athenian ships blockaded it by sea. When fighting broke out, the wall prevented Pharnabazus’s army from joining in, and the Spartan commander Hippocrates was killed. But the Spartan army escaped into the town, creating a stalemate. Because of the proximity of Pharnabazus’s considerable forces, the Athenians then did something unprecedented. With Alcibiades absent in search of money wherever he could get it, Xenophon reports,
the other generals came to an understanding with Pharnabazus that they would spare Chalcedon in exchange for a payment of twenty talents; the satrap would also conduct Athenian ambassadors to the King. Oaths were also exchanged to the effect that Chalcedon would pay the Athenians the same amount as in the past and make up all arrears of payment and that the Athenians would undertake no hostile actions against Chalcedon until the ambassadors had returned from the King.
This innovative arrangement spared everyone the trouble of a siege and scored the Athenians a welcome infusion of cash.
Sitting on the north shore of the Propontis, Selymbria was also in Alcibiades’ sights. Fortunately for the Selymbrians, though the determined Athenian commander had raised cash and Thracian troops in Gallipoli, he was hoping to husband his resources for the coming attack on his chief target, Byzantium, and taking their city by storm was not part of his game plan; rather he arranged for a pro-Athenian party in the town to open the gates to him during the night. The Athenians then placed a garrison in the city, collected some money, and doubled back to join Theramenes and Thrasyllus at Byzantium. Founded in the seventh century primarily by colonists from Megara, Byzantium’s location at the entrance to the Black Sea led it to prosper as a center of trade, and strategically it benefited from its position as a chokepoint for the control of grain from Ukraine. It had entered the Delian League voluntarily in 478/77.
The forces in this key stronghold were about evenly matched when the Athenian generals attacked it in 408, and there seemed to be no way the Athenians could take the city by sheer force. The Peloponnesians were commanded by Clearchus, and he was the only Spartan present; the others, besides the Byzantines themselves, were Megarians (possibly because of the role of Megara in founding the city), Boeotians, perioeci, and neodamodeis. But the total number resisting was large, for Byzantium was a substantial city. The Athenians had built siege engines and attacked the city’s fortifications both at long range and at close quarters, but to no avail. In their arsenal, however, was a secret weapon: Clearchus’s own disposition. Clearchus was a hardy soldier and had given the Athenians a run for their money at Cyzicus, but now at Byzantium his conduct evidently evoked that of an earlier Spartan at Byzantium, the Persian War general Pausanias, who had taken over as regent for Leonidas’s underage son Pleistarchus after Leonidas’s heroic death at Thermopylae and thoroughly alienated the Greeks by his arrogance. Clearchus seems to have been an unpleasant man, and lacking in judgment as well. Having given all the food in the city to the Spartan and allied soldiers, he let the populace die of hunger, and wanting money to pay his troops and build ships with which to distract the Athenians, he went off in search of funds, leaving the city in the charge of subordinates.
Clearchus plainly did not believe that anyone would betray the key stronghold in the Hellespont to the Athenians, but his confidence was misplaced. A number of prominent Byzantines were so alienated that they conspired with Alcibiades to do just this. Circulating a story that the Athenians were leaving for Ionia, Alcibiades led his forces just far enough away from Byzantium to make the tale credible, but he remained close enough to return at night to attack the Peloponnesian ships in the harbor. When fighting broke out between those loyal to Athens and those persevering in their fidelity to Sparta, Alcibiades issued a proclamation guaranteeing the safety of the Byzantines if they would lay down their arms. They did so—not before killing a good number of the Peloponnesian army—and were then returned to their status as an Athenian ally; no Byzantine was killed or exiled, and the city was not garrisoned. Plainly the Athenians were practicing a gentler policy with the idea of paving the way for peace.
Their request at Chalcedon for a parley with Darius had reflected those hopes for peace. The Spartans, after all, had violated their treaty with the Persians by offering to make a separate peace with Athens. Would the king perhaps now be receptive to overtures from the other side in the conflict?
Unfortunately, the Athenian ambassadors had nothing to offer him, for unlike the Spartans, they possessed territory in Ionia that paid them tribute, and they were not about to give it up. What could have come of a conference with Darius, one cannot imagine. Perhaps the Athenians simply wished to call the king’s attention to the Spartans’ perfidy in offering them a separate peace and to dissuade him from further subsidizing them. But no such meeting ever took place, for on their journey—which Pharnabazus saw to it was a slow and laborious one—they encountered the Spartan Boeotius and his fellow ambassadors returning from Darius’s court, and they brought bad news: the Spartans, they reported, “had gotten everything they wanted from the King.” Worse yet, the Spartans were accompanied by their new ally Cyrus, the king’s son, who carried with him a letter from his father explaining that the sixteen-year-old youth would henceforth be taking charge of much of the coastal area and helping the Spartans in the war. Thus the Athenians found their substantial military gains offset by a notable diplomatic—and financial—loss.