Second Persian invasion of Greece

Spring 480 BCE: the army leaves Sardis

At the beginning of spring in 480 BCE, with the canal at Athos, the Hellespont bridges and the rest of the preparations complete, Xerxes and his army departed Sardis for Abydos.

By the Herodotean chronology those preparations had taken four full years, from spring 484. Roads, depots, bridges and the canal all came before the march.

Two bridges, split by traffic

At the Hellespont — the modern Dardanelles, not the Bosporus — the force prepared a ceremonial crossing on two pontoon bridges joining Asia to Europe.

Herodotus says the road was strewn with myrtle and incense was burned, and that at sunrise Xerxes poured a libation from a golden vessel and cast offerings into the water. Troops and horses used the bridge nearer the Black Sea; baggage animals and the service train used the one nearer the Aegean.

What the crossing changed

Once across, the land army could advance through Persian-controlled Thrace and Macedonia, supported by a fleet moving along the coast and by supplies staged in advance. Greece now faced a coordinated land-and-sea invasion rather than the maritime expedition that had ended at Marathon.

The force was drawn from across the empire rather than one people: Herodotus's traditional catalogue names 46 peoples, his own categories and not modern nations. His million-scale totals are rejected by modern scholars, whose estimates vary widely among themselves.

Even the omen does not survive checking. Herodotus places an ominous daytime darkness at the departure, but no solar eclipse fits Sardis in spring 480, and commentary suggests separate eclipse traditions were conflated.