The beginnings of the Athenian democracy coincide with the Persian Wars. The Persians were naive enough and arrogant to believe that they could easily conquer Athens-and Greece for that matter-with their enormous armies and fleet. Three times they invaded Greece; three times they were repelled. At the end of those wars Athens emerged as the main city-state of Greece, the controlling power of the Delian League, with colonies all over the Mediterranean, a city of freedom, affluence and culture. In 499 B.C. the Greek Ionian cities in Asia Minor-led by Miletos and assisted by Athens-revolted against Persian oppression. This must have caused Darius, the Persian king, to become even more determined to implement a plan, which he had been contemplating for many years, the subjugation of the European Greeks.

The first Persian invasion of Greece was staged in 492 B.C. when Darius sent his son-in-law Mardonios on a military expedition to conquer Thrace and Macedonia. Although Mardonios succeeded in his objective, he was forced to return to Persia because his accompanying fleet was destroyed by stormy seas while rounding the Mt. Athos peninsula. Two years later Darius attempted a second invasion of Greece. Under the advise of Hippias, the exiled former tyrant of Athens, who resided in Susa, the Persian capital, Darius sent his fleet with two commanding generals, Datis and Artaphernes, and a sizable army to land at the shores of Marathon on the coast of Attica, about 32 miles from Athens. Their aim was to storm Athens. The Athenians sent out a runner, Pheidippides, to ask Sparta, 150 miles to the south, for help, but the Spartans were busy with religious festivals and unable to assist. The Athenians were forced to take on the invaders on their own. Miltiades, the Athenian general, prevailed over the city's chief-of-war that the Athenians should engage the Persians immediately before they have an opportunity to advance to the city. Miltiades' military tactics were ingenious. His battle plan gave the small Athenian army victory at Marathon over the Persian invaders' vast superiority. The Persians were forced to retreat back to Asia.

Persia's third attempt to conquer Greece came ten years later. Darius' successor Xerxes (his son), amassed an overwhelming force of land troops and ships and invaded Greece once more. Thirty-one Greek city-states-led by Athens and Sparta-formed an alliance to fight the foreign enemy. The Greeks decided to make a stand against the advancing Persian army at the narrow pass of Thermopylae, 150 miles away from Athens. The Spartan king Leonidas commanded the Greek forces. Facing incredible odds Leonidas dismissed most of the other cities' contingents and remained at Thermopylae with just 300 Spartans to fight the massive Persian troops. After a heroic resistance the defenders were overcome and killed. Faced with the imminent arrival of the Persian army, the Athenians were persuaded by their leader, Themistocles, to put their trust in their naval forces and confront the invaders at sea. The Athenians' fleet-built with the profits from the lucky strike of a rich vein of silver in the Lavrion mines (483) - was the "brainchild" of Themistocles, who believed that Athens should place emphasis on naval supremacy. As an archon he committed Athenians to invest a large part of Lavrion's windfall to the development of a strong fleet. As the Persians approached Athens Themistocles had the women and children of Athens moved to a safe area in Peloponnese and retreated with the Athenian fleet to the island of Salamis. The Persians entered Athens and devastated the city. Their fleet was lured by Themistocles to the narrow straight between Salamis and the mainland, which was too narrow for the enormous Persian fleet; the naval battle which ensued brought a tremendous victory to the Athenians and great personal glory to Themistocles. Although Athens was destroyed the Persians were repelled once more. Xerxes withdrew from Greece but left behind an army of 100,000 men under Mardonios, who camped out for the winter awaiting the time for an new attack. The Persian danger was finally uniting the Greeks. The Spartans joined in, as did the cities of Megara and Plataea. Together they advanced on Mardonios at Plataea in 479 B.C. Mardonios was killed and his army defeated. At about the same time the Greek fleet, half of it Athenian, met what was left of the Persian fleet at Mycale, across the island of Samos, and destroyed it. The last episode was played out at the Eurymedon River at Pamphylia some nine years later. There, Kimon, the Athenian general, delivered the final blow on the Persian army and navy, bringing an end to the long chapter of Persian efforts to dominate Greece.