The inaction of the Asiatic commanders, during this interval,
appears strange at first sight; but Hippias was with them, and
they and he were aware of their chance of a bloodless conquest
through the machinations of his partisans among the Athenians.
The nature of the ground also explains, in many points, the
tactics of the opposite generals before the battle, as well as
the operations of the troops during the engagement.

The plain of Marathon, which is about twenty-two miles distant
from Athens, lies along the bay of the same name on the north-
eastern coast of Attica. The plain is nearly in the form of a
crescent, and about six miles in length. It is about two miles
broad in the centre, where the space between the mountains and
the sea is greatest, but it narrows towards either extremity, the
mountains coming close down to the water at the horns of the bay.
There is a valley trending inwards from the middle of the plain,
and a ravine comes down to it to the southward. Elsewhere it, is
closely girt round on the land side by rugged limestone
mountains, which are thickly studded with pines, olive-trees, and
cedars, and overgrown with the myrtle, arbutus, and the other low
odoriferous shrubs that everywhere perfume the Attic air. The
level of the ground is now varied by the mound raised over those
who fell in the battle, but it was an unbroken plain when the
Persians encamped on it. There are marshes at each end, which
are dry in spring and summer, and then offer no obstruction to
the horseman, but are commonly flooded with rain, and so rendered
impracticable for cavalry, in the autumn, the time of year at
which the action took place.