Herodotus describes the approach of Cyrus and his war against Babylon in the following manner: "When on his march against Babylon he came to the Gyndes (now the Diala), which falls into the Tigris, and crossed it, one of the sacred white horses was carried away by the stream. Cyrus was angry, and threatened that he would make the river so insignificant that a woman should cross it without wetting her knee. With this view he drew 180 lines on each side of the river, and bade his army dig a channel on every line; and as a great multitude was employed, the work was finished, but it occupied the whole summer, so that Cyrus did not lead his army against Babylon till the second spring. The Babylonians marched out of the city and awaited his attack. When Cyrus came up the Babylonians joined battle; they were defeated, and driven into the walls. They had known for a long time that Cyrus would not remain at rest, for they had seen how he had reduced all nations alike, and therefore they had collected provisions for many years in the city. The siege, therefore, caused them no alarm; but Cyrus was in difficulties, for time passed away, and he made no advance. Afterwards he did as follows, whether it was that some one suggested the plan to him, or whether he discovered it for himself. He placed part of his army where the river flows into the city, and part where it flows out, and bade them enter the city by the river as soon as it could be forded. After he had given them orders, he went with the bulk of his army to the basin, which the queen of the Babylonians had caused to be excavated, and did what she had done with the basin and the river. By leading the river through the opening into this basin, which was a marsh, he made the old bed so that it could be forded. When this had been done, and the water of the river had fallen to such an extent that it reached the middle of a man's thigh, the Persians who had been placed near the city forced their way into Babylon along the bed of the river. Had the Babylonians previously known or suspected what Cyrus intended, the Persians would not have passed unnoticed into the walls; had they closed the gates leading from the city to the river, and mounted the walls which line the banks, they would have caught the Persians in a trap as it were, and they would have perished miserably. But the Persians came quite unexpectedly. The outer parts of the city had been already taken while those in the centre, who, as the Babylonians say, knew nothing of the matter, owing to the extent of the city, were dancing and making merry--for it so happened that a festival was being celebrated--until they at length discovered their misfortune."