Heya. Nice username.

We know much less about the Ionian Revolt than we would like to. Our only source for the events is the very unsatisfactory account in Herodotos' Histories. While Herodotos was from Halikarnassos in Asia Minor, and presumably knew a lot about the affairs of the Greeks in those parts, his tale of the Ionian Revolt is simplistic and full of holes. Much of what we claim to know about the conflict is speculation based on plausibilities.

Herodotos has it that the entire Revolt was the responsibility of Histiaios, the tyrant of Miletos, and his deputy Aristagoras. These men were afraid that the Persians would strip them of their lofty position, and therefore enticed the other cities on the west coast of Asia Minor to revolt. He does not explain how they did this, or why the Greeks would be so keen to revolt against Persia in the first place. Modern theories include bitterness over being excluded from the Aegean trade network, over the high tribute imposed by the Persians, or over the tyrants that were imposed on them by the Great King. There is hardly a whisper of any of this in Herodotos. Indeed, the Greek cities (with one exception) let their tyrants go free after deposing them, suggesting they were not the focus of particular hatred; when the revolt was put down and Mardonios was sent to reassess the tribute, it was established that the previous level had been fair, and it was kept unchanged by the Athenians when they "liberated" the region and started levying their own tribute. Basically, we don't know why the Ionian Revolt happened at all.

Something similar can be said about the involvement of allies from Old Greece. Most Greeks clearly wanted nothing to do with the Ionian business of waking a sleeping lion, but Athens and Eretria sent a small force in support. Why? Again, Herodotos doesn't say. In his version, Aristagoras simply went from city to city trying to persuade people to help him out, spinning them tales of untold riches ready for the taking and cowardly Persians unable to mount any effective resistance. His sales pitch failed when he tried it on King Kleomenes of Sparta, but it succeeded in the Assembly at Athens; all Herodotos has to say about it is that this proves "it is easier to deceive many than one". Why the Athenians thought the idea was attractive is left for the reader to decide. Ancestral ties to the Ionians in Asia Minor is one possible explanation, although there is little in Herodotos to confirm that the Athenians would have cared that much; he claims the Eretrians only went because the Milesians had supported them in war in the past.

It should be noted, though, that the force sent by the Athenians and Eretrians was very small - 25 triremes in total (20 Athenian and 5 Eretrian). Given that the Ionians themselves mustered well over 300 triremes for the battle of Lade, it is hard to imagine that either Athens or Eretria was trying to make a stand here and commit to the success of the Ionians.

More likely, they just wanted a slice of the pie. The large forces commanded by the rebellious cities (which were also joined by the Karians, the cities on the Hellespont and the Greeks on Cyprus) may have made them optimistic about the outcome. They may have been happy to believe Aristagoras' tale about the great plunder they could get from the Persians. Their actions confirm this picture: they crossed the Aegean, helped the Ionians sack and burn the local Persian administrative centre of Sardis, and then went home. When the Persians struck back, the Athenians were notably absent, and they would offer no more support to the Ionians for the remainder of the Revolt. This hardly sounds like the behaviour of a mother city protecting its ancient colonies.

After the Persians responded in force and the Revolt was put down, many Greeks on the mainland roundly blamed the Athenians for bringing themselves to the Great King's attention. Their actions provided the Persians with a nice pretext to expand further west. The campaign that ended at Marathon is mostly known for the result of that battle; it is often forgotten that the Persians, before they came to Athenian territory, landed on Euboia, assaulted Eretria, and burned it to the ground in retribution for its support of the Ionians at Sardis.

The short version, then, is probably that the Athenians and Eretrians were to some extent blinded by greed, and overly impressed with the forces mustered by the rebellious cities and regions of Asia Minor. A fleet of 350 triremes must have looked to them like it could conquer the whole world - until the Persians sent a fleet of 600 to crush it. The mainland Greeks had no previous experience fighting an enemy like the Persian empire, and it is likely that they simply did not know who they were dealing with.

It wasn't the Greeks but just the Athenians and a small group from a tiny city state called Eritrea on the island of Boeotia. Athenians were Ionian and sent colonies to the area that later became known as Ionia in the Dark Ages after the fall of the Mycenaeans.