The First Persian War
After the Ionian revolt ended, Darius decided to expand his empire's territories. In 493 BC the Persians defeated the remains of the Ionian revolt. This was a very good chance for Darius to extend his empire and he did so by acquiring the islands of East Aegean and the Propontis. After the revolt Darius selected his son-in-law Mardonius for resettlement of the cities destroyed in the revolt. This change was shockingly civil compared to the known cruel Persian rulers. Democracy was introduced, tax system was more liberal, and prisoners were released and sent back to hometowns. Darius civil attitude was a calculatory move to pressurize the Greek states to surrender, which did so. But Athens and Sparta were exceptions.
In 492 BC Mardonius tried to control as many Hellenic cities as he could. While the army was sent to capture Hellespont, he along with his navy took over Ionia.
From there he joined his army in Hellespont, capturing Thrace and Macedon on his way. While Thrace surrendered without revolting, Macedon was reduced from an ally to a city-state. He then moved to Thassos but luck would have it, he faced a powerful storm where nearly 20,000 men of his army were killed.
Datis and Artaphernes gathered force to teach Attica and Eretria a lesson for supporting Ionia.
Traveling from Cilicia to Rhodes, they moved upto Samos and then to Naxos. The residents there surrendered themselves to Eretria. Eretria was captured and looted and then surrendered the city back.