Moreover, the poorer portion of these were unprovided with the equipments, and untrained to the operations of the regular infantry.  Some detachments of the best-armed troops would be required to garrison the city itself and man the various fortified posts in the territory, so that it is impossible to reckon the fully equipped force that marched from Athens to Marathon, when the news of the Persian landing arrived, at higher than ten thousand men.[41]

[Footnote 41:  The historians, who lived long after the time of the battle, such as Justin, Plutarch, and others, give ten thousand as the number of the Athenian army.  Not much reliance could be placed on their authority if unsupported by other evidence; but a calculation made for the number of the Athenian free population remarkably confirms it.]

With one exception, the other Greeks held back from aiding them.  Sparta had promised assistance, but the Persians had landed on the sixth day of the moon, and a religious scruple delayed the march of Spartan troops till the moon should have reached its full.  From one quarter only, and that from a most unexpected one, did Athens receive aid at the moment of her great peril.

Some years before this time the little state of Plataea in Boeotia, being hard pressed by her powerful neighbor, Thebes, had asked the protection of Athens, and had owed to an Athe man army the rescue of her independence.  Now when it was noised over Greece that the Mede had come from the uttermost parts of the earth to destroy Athens, the brave Plataeans, unsolicited, marched with their whole force to assist the defence, and to share the fortunes of their benefactors.

The general levy of the Plataeans amounted only to a thousand men; and this little column, marching from their city along the southern ridge of Mount Cithaeron, and thence across the Attic territory, joined the Athenian forces above Marathon almost immediately before the battle.  The reenforcement was numerically small, but the gallant spirit of the men who composed it must have made it of tenfold value to the Athenians, and its presence must have gone far to dispel the cheerless feeling of being deserted and friendless, which the delay of the Spartan succors was calculated to create among the Athenian ranks.[42]

[Footnote 42:  Mr. Grote observes that “this volunteer march of the whole Plataean force to Marathon is one of the most affecting incidents of all Grecian history.”  In truth, the whole career of Plataea, and the friendship, strong, even unto death, between her and Athens form one of the most affecting episodes in the history of antiquity.  In the Peloponnesian war the Plataeans again were true to the Athenians against all risks, and all calculation of self-interest:  and the destruction of Plataea was the consequence.  There are few nobler passages in the classics than the speech in which the Plataean prisoners of war, after the memorable siege of their city, justify before their Spartan executioners their loyal adherence to Athens.]