If the fleet did remain at the Ister, which seems to be one of the few absolutely reliable statements in the story, the fact itself is strong presumptive evidence that Darius did not intend to go far beyond that river. Ktesias says he only proceeded fifteen days’ march. Strabo implies that he never reached the Dniester.
Inasmuch as the reliability of Herodotus as an historian is in question, it is important to make an attempt to surmise, in so far as possible, what was the source or sources of this extraordinary tale which he has preserved.
It must be remembered, in the first place, that at the time at which he wrote, anything of the nature of reliable information with regard to events before the war of 480 must have been very difficult to obtain. The palpable gaps in the story of the Ionian Revolt, the confusion in the account of the relations between Athens and Ægina, the meagreness of the story of Marathon, are striking proofs that such was the case; and if he experienced such manifest difficulty in arriving at a detailed knowledge of the great events of the beginning of the fifth century, in which Greeks played a foremost part, how much greater difficulty must he have experienced in gaining information as to the events of the later years of the sixth century, in which the part played by the Greeks was but secondary?
It seems probable that his sources of information in the present instance were two in number:—
(1) A tale current in the Athens of his own day, which had come thither by way of the principality of Miltiades in the Thracian Chersonese.
(2) Reports collected by the historian himself, either in the course of a journey to the Greek colonies on the north coast of the Euxine, or from persons who were natives of those parts, or had visited them.
To the first of these must be attributed the account which he gives of the events on the Danube, and especially the celebrated tale of the proposal of Miltiades to break down the bridge and leave Darius to his fate.
The story is one of the most famous in Greek History. Twice, it is said, did the Scythians, while Darius with his army was still far north of the river, ride down to the Ister and call upon the Greeks to break down the bridge. H. iv. 133, 136. On the first occasion the Ionians promised to do so. The tale seems to imply that the promise was merely made with a view to getting rid of the Scythians. On the second occasion the Scythians made much the same appeal, calling on the Ionians to strike one grand, effective blow for their freedom.
It is unnecessary to dwell on the minor difficulties of the tale, how, for instance, it came about that the Scythians knew of Darius’ orders that the bridge should be loosed after the expiration of sixty days.
H. iv. 137.