Alkibiadês had employed his period of absence in capturing Selymbria, from whence he obtained a sum of money, and in getting together a large body of Thracians, with whom he marched by land to Byzantium. That place was now besieged, immediately after the capitulation of Chalkêdon, by the united force of the Athenians. A wall of circumvallation was drawn around it, and various attacks were made by missiles and battering engines. These, however, the Lacedæmonian garrison, under the harmost Klearchus, aided by some Megarians under Helixus, and Bœotians under Kœratadas, was perfectly competent to repel. But the ravages of famine were not so easily dealt with. After the blockade had lasted some time, provisions began to fail; so that Klearchus, strict and harsh, even under ordinary circumstances, became inexorable and oppressive, from exclusive anxiety for the subsistence of his soldiers; and even locked up the stock of food while the population of the town were dying of hunger around him. Seeing that his only hope was from external relief, he sallied forth from the city to entreat aid from Pharnabazus; and to get together, if possible, a fleet for some aggressive operation that might divert the attention of the besiegers. He left the defence to Kœratadas and Helixus, in full confidence that the Byzantines were too much compromised by their revolt from Athens to venture to desert Sparta, whatever might be their suffering. But the favorable terms recently granted to Chalkêdon, coupled with the severe and increasing famine, induced Kydon and a Byzantine party to open the gates by night, and admit Alkibiadês with the Athenians into the wide interior square called the Thrakion. Helixus and Kœratadas, apprized of this attack only when the enemy had actually got possession of the town on all sides, vainly attempted resistance, and were compelled to surrender at discretion: they were sent as prisoners to Athens, where Kœratadas contrived to escape during the confusion of the landing at Peiræus. Favorable terms were granted to the town, which was replaced in its position of a dependent ally of Athens, and probably had to pay up its arrears of tribute in the same manner as Chalkêdon.[193] [193] Xenoph. Hellen. i, 3, 15-22; Diodor. xiii, 67; Plutarch, Alkib. c. 31. The account given by Xenophon of the surrender of Byzantium, which I have followed in the text, is perfectly plain and probable. It does not consist with the complicated stratagem described in Diodorus and Plutarch, as well as in Frontinus, iii, xi, 3; alluded to also in Polyænus, i, 48, 2.