In Ionia (the modern Aegean coast of Turkey), the Greek cities, which included great centres such as Miletus and Halicarnassus, were unable to maintain their independence and came under the rule of the Persian Empire in the mid-6th century BC. In 499 BC that region’s Greeks rose in the Ionian Revolt, and Athens and some other Greek cities sent aid, but were quickly forced to back down after defeat in 494 BC at the Battle of Lade. Asia Minor returned to Persian control.
In 492 BC, the Persian general Mardonius led a campaign through Thrace and Macedonia. He was victorious and again subjugated the former and conquered the latter, but he was wounded and forced to retreat back into Asia Minor. In addition, a fleet of around 1,200 ships that accompanied Mardonius on the expedition was wrecked by a storm off the coast of Mount Athos. Later, the generals Artaphernes and Datis led a successful naval expedition against the Aegean islands.
In 490 BC, Darius the Great, having suppressed the Ionian cities, sent a Persian fleet to punish the Greeks. (Historians are uncertain about their number of men; accounts vary from 18,000 to 100,000.) They landed in Attica intending to take Athens, but were defeated at the Battle of Marathon by a Greek army of 9,000 Athenian hoplites and 1,000 Plataeans led by the Athenian general Miltiades. The Persian fleet continued to Athens but, seeing it garrisoned, decided not to attempt an assault.
In 480 BC, Darius’ successor Xerxes I sent a much more powerful force of 300,000 by land, with 1,207 ships in support, across a double pontoon bridge over the Hellespont. This army took Thrace, before descending on Thessaly and Boeotia, whilst the Persian navy skirted the coast and resupplied the ground troops. The Greek fleet, meanwhile, dashed to block Cape Artemision. After being delayed by Leonidas I, the Spartan king of the Agiad Dynasty, at the Battle of Thermopylae (a battle made famous by the 300 Spartans who faced the entire Persian army), Xerxes advanced into Attica, and captured and burned Athens. The subsequent Battle of Artemisium resulted in the capture of Euboea, bringing most of mainland Greece north of the Isthmus of Corinth under Persian control. However, the Athenians had evacuated the city of Athens by sea before Thermopylae, and under the command of Themistocles, they defeated the Persian fleet at the Battle of Salamis.
In 483 BC, during the period of peace between the two Persian invasions, a vein of silver ore had been discovered in the Laurion (a small mountain range near Athens), and the hundreds of talents mined there were used to build 200 warships to combat Aeginetan piracy. A year later, the Greeks, under the Spartan Pausanias, defeated the Persian army at Plataea. The Persians then began to withdraw from Greece, and never attempted an invasion again.
The Athenian fleet then turned to chasing the Persians from the Aegean Sea, defeating their fleet decisively in the Battle of Mycale; then in 478 BC the fleet captured Byzantium. At that time Athens enrolled all the island states and some mainland ones into an alliance called the Delian League, so named because its treasury was kept on the sacred island of Delos. The Spartans, although they had taken part in the war, withdrew into isolation afterwards, allowing Athens to establish unchallenged naval and commercial power.