On the available evidence, positive statement as to the proportion of numbers between the two armies which fought in the battle is impossible. All that can be said is that it is highly improbable that the Persians outnumbered the Greeks by two to one, and quite possible that the disproportion between the two armies was not very great. It may be well now to form a conjecture as to the strategy which prompted the Persian general to make this disposition of their forces. It would seem that, fearing the arrival of the Spartans at Marathon, or even at Athens, they had determined to carry out the plan they had intended to put into operation as soon as they should receive the signal from their Athenian confederates. The signal had not been given; but they could not wait. They must take their chance at Athens, and hope to find the treason there in a sufficiently forward state to render their entrance into the city possible. So they divided their forces, leaving a sufficient number at Marathon to occupy the attention of the Athenians and to make it dangerous for them to move on Athens. These troops had also to cover the embarkation of the major part of the army, including the cavalry. With this latter part of their force they intended to sail round and to attack Athens before either the Athenians could come up from Marathon or the Spartans could arrive from Sparta. It was for some such eventuality as this that Miltiades had been waiting. He and his colleagues must have seen clearly that the Persians could not afford to continue indefinitely a policy of delay. They must have divined also that the delay could have but one meaning, namely, that the enemy were waiting for a sign from their friends in Athens. It is not difficult to understand the motives which actuated either side at this crisis in the campaign. The Persian troops left at Marathon had a double duty to perform. They had to cover the embarkation of the rest of the army. They had, also, to do everything in their power to detain the Athenian army at Marathon. Had not this second duty devolved upon them, they would doubtless have remained north of the Charadra, and would probably have defended the line of that stream-bed. But in that case the Athenians would have been given so long a start in their retirement upon Athens, that it would have been difficult, if not impossible, to harass and delay their march. Thus it became necessary to move nearer to the Athenian encampment. They crossed the Charadra, and took up a position prepared alike for battle or pursuit.