In the spring of 498 BCE, an Athenian force of twenty triremes, accompanied by five from Eretria, set sail for Ionia. They joined up with the main Ionian force near Ephesus. Declining to personally lead the force, Aristagoras appointed his brother Charopinus and another Milesian, Hermophantus, as generals.

This force was then guided by the Ephesians through the mountains to Sardis, Artaphernes's satrapal capital. The Greeks caught the Persians unaware, and were able to capture the lower city. However, Artaphernes still held the citadel with a significant force of men. The lower city then caught on fire, Herodotus suggests accidentally, which quickly spread. The Persians in the citadel, being surrounded by a burning city, emerged into the market-place of Sardis, where they fought with the Greeks, forcing them back. The Greeks, demoralised, then retreated from the city, and began to make their way back to Ephesus.

Herodotus reports that when Darius heard of the burning of Sardis, he swore vengeance upon the Athenians (after asking who they indeed were), and tasked a servant with reminding him three times each day of his vow: "Master, remember the Athenians".