Cyrus carried on the siege for some time with no prospect of success against its “mountain-high” walls, and its brazen, iron-barred gates, protected by an impassable moat. But midsummer coming on, and with it the grand Babylonian festival in honor of the god Tammuz, Cyrus determined on a stratagem. Knowing of the boundless license in which it was the wont of the Babylonians to indulge in that celebration, Cyrus went up the Euphrates a considerable distance, and dug channels by which to turn its waters from their course. As the Euphrates flowed through the city under the great walls, Cyrus's plan was to draw the water down so shallow that men could wade without difficulty, and have them march into the city by the river-bed. But even that would have been of no avail, had not the Babylonians given themselves up to utter heedlessness in their wild orgies. For on each bank of the river, within the city, stood walls about a hundred and fifty feet high, with double gates of solid brass; and if only these gates had been shut or even watched, the Persians in the bed of the river would have been certainly caught in a trap.