The siege of Byzantium in (408 was an
Athenian victory that saw them regain control over the Bosphorus, and remove a
threat to Athens's food supplies from the Black Sea (Great
War). Byzantium had been part of the Athenian Empire, but it had rebelled
after the Athenian disaster at Syracuse, and by 408 was held by a mixed
garrison of Byzantines, Perioci (free non-citizens of Sparta), Neodamodes
(Helots freed after serving in the Spartan army), Megarians and Boeotians, all
commanded by the Spartan governor
The Athenian army, at least 5,000 strong, was commanded by
Alcibiades. In the
spring of 408 they had besieged Chalcedon, on the opposite side of the
Bosphorus, and had won a victory outside the city. Theramenes had then come to
an agreement with the Persian satrap
Pharnabazus in which
the Athenians agreed to halt military activities against Chalcedon in return
for a payment of 20 talents, as well as the regular tribute from Chalcedon and
free passage for an embassy to visit the Persian emperor.
The main focus of the Athenian military then moved across the water to
Byzantium. The Athenians built siege lines around the city, cutting it off by
land and sea. They also positioned sharpshooters around the city, and carried
out a number of unsuccessful assaults on the walls. The turning point of the
siege came when Clearchus decided to leave the city to collect money from
Pharnabazus and to raise a fleet to harass the Athenians at sea. In his absence
a number of Byzantines, angered by the way most food in the city was going to
the Peloponnesian troops, decided to surrender the city to the Athenians.
Our two main sources give different accounts of the surrender. According to
Xenophon the Byzantine plotters simply let the Athenians into the city. The
garrison found them already in occupation of the centre of the city, and had no
choice but to surrender.
Diodorus Siculus gives a rather more complex account. In order to convince the
garrison that they were abandoning the siege, the Athenian fleet put to sea and
their army withdrew, but under cover of darkness their fleet launched a noisy
attack on the harbour area, while the army hid close to the walls. The garrison
rushed to the harbour to fight off the naval attack, at which point the
Athenian supporters inside the city signalled to the besieging army, which
entered the city using ladders. Half of the garrison rushed back to the walls,
and a fierce battle broke out. The battle only ended after Alcibiades announced
that no harm would be done to the Byzantines, at which point they changed
sides. In both accounts the captured prisoners were taken back to Athens.
Byzantium was treated generously, and was re-admitted to the Empire as allies.
In the aftermath of this victory Alcibiades was finally able to return to
Athens after years in exile, although his return to favour would be short
lived, and in 407 he would return to exile.