THE IONIAN REVOLT.--Hardly were the Greeks in possession of liberty when they were compelled to measure their strength with the mighty Persian Empire. The cities of Asia Minor groaned under the tyranny of their Persian rulers, and sighed for freedom. At length, under propitious circumstances, _Miletus_ rose in revolt under the lead of _Aristagoras_. Alone of the Grecian cities, Athens, and Eretria on the island of Euboea, sent help. The insurrection was extinguished in blood: its leaders perished. Miletus was destroyed by the enemy 495 B.C.; and the Ionian towns were again brought under the Persian yoke, which was made heavier than before. The Persian monarch, _Darius_, swore vengeance upon those who had aided the rebellion. THE BATTLE OF MARATHON.--_Mardonius_, the son-in-law of Darius, moved with a fleet and an army along the Ægean coast. A storm shattered the fleet upon the rocky promontory of Athos, and the land force was partly destroyed by the Thracians. Mardonius retreated homeward. The heralds who came to demand, according to the Persian custom, "water and earth" of Athens and Sparta, were put to death. Enraged at these events, Darius sent a stronger fleet under _Datis_ and _Artaphernes_. They forced _Naxos_ and the other _Cyclades_ to submission, captured and destroyed _Eretria_, and sent off its inhabitants as slaves to the interior of Asia. Guided on their path of destruction by the Athenian refugee, _Hippias_, the Persians landed on the coast of Attica, and encamped on the shore adjacent to the plain of _Marathon_. The Athenians sent _Philippides_, one of the swiftest of couriers, to Sparta for assistance, who reached that city, a hundred and thirty-five or a hundred and forty miles distant, the next day after he started. He brought back for answer that the Spartans were deterred by religious scruples from marching to war before the full moon, which would be ten days later. There was a Greek, as well as a Judaic, Pharisaism. Left to themselves, the Athenians were fortunate in having for their leader _Miltiades_, an able and experienced soldier, who had been with the Persians in the Scythian campaign. At the head of the Athenian infantry, ten thousand in number, whose hearts were cheered before the onset by the arrival of a re-inforcement of one thousand men, comprising the whole fighting population of the little town of _Platæa_, Miltiades attacked the Persian army, ten times as large as his own. The Athenians ran down the gentle slope at Marathon, shouting their war-cry, or pæan, and, after a fierce conflict, drove the Persians back to their ships, capturing their camp with all its treasures (Sept. 12, 490 B.C.). This brilliant victory was not the end of danger. The Greek watchmen saw a treacherous signal, a glistening shield, on _Mount Pentelicus_, put there to signify to the Persians that Athens was open to their attack. In that direction, round Cape Sunium, the Persian fleet sailed. But