14 events the sources record for this year, grouped by region.
What happened
West Asia (2)
Datis and Artaphernes reach Asia and take the Eretrian captives to Susa (Herodotus, Histories 6.119)
Darius, hearing of Marathon, furiously orders the army to be mustered; he dies after the Egyptian revolt (reign of 36 years) (Herodotus, Histories 7.1-4)
Southern Europe (12)
Athens fights a naval battle with Aegina using seventy ships and wins; afterwards the Aeginetans attack the Athenian fleet and capture four ships (Herodotus, Histories 6.92-93)
Datis and his company load horses and troops onto ships in Cilicia and sail via Ionia to Naxos; the Naxians flee to the mountains (Herodotus, Histories 6.94-96)
Datis does not touch Delos and places the ships in two spots; Delos is said to have had an earthquake (Herodotus, Histories 6.97-98)
Persia subdues Carystus, lands at Eretria, and besieges and takes the city (Herodotus, Histories 6.98-101)
After conquering Eretria, Persia sails for Attica a few days later and lands at Marathon (Herodotus, Histories 6.102)
Athens, led by ten generals, marches to Marathon; Plataea sends reinforcements (Herodotus, Histories 6.103-108)
At Miltiades' urging, Athens resists and fights long; Polemarchus and Callimachus die (Herodotus, Histories 6.109-114)
The Persians lose seven ships and sail around Sunium; Athens returns to the city first and guards it; 6,400 Persians and 192 Athenians die (Herodotus, Histories 6.115-117)