[9] At which Cyrus said, "Well, Chrysantas, we must forego what is beyond our power: but let us measure off at once the work for each of us, set to, and dig a trench as wide and as deep as we can, that we may need as few guards as possible." [10] Thereupon Cyrus took his measurements all round the city, and, leaving a space on either bank of the river large enough for a lofty tower, he had a gigantic trench dug from end to end of the wall, his men heaping up the earth on their own side. [11] Then he set to work to build his towers by the river. The foundations were of palm-trees, a hundred feet long and more--the palm-tree grows to a greater height than that, and under pressure it will curve upwards like the spine of an ass beneath a load. [12] He laid these foundations in order to give the impression that he meant to besiege the town, and was taking precautions so that the river, even if it found its way into his trench, should not carry off his towers. Then he had other towers built along the mound, so as to have as many guard-posts as possible. [13] Thus his army was employed, but the men within the walls laughed at his preparations, knowing they had supplies to last them more than twenty years. When Cyrus heard that, he divided his army into twelve, each division to keep guard for one month in the year. [14] At this the Babylonians laughed louder still, greatly pleased at the idea of being guarded by Phrygians and Lydians and Arabians and Cappadocians, all of whom, they thought, would be more friendly to themselves than to the Persians. [15] However by this time the trenches were dug. And Cyrus heard that it was a time of high festival in Babylon when the citizens drink and make merry the whole night long. As soon as the darkness fell, he set his men to work. [16] The mouths of the trenches were opened, and during the night the water poured in, so that the river-bed formed a highway into the heart of the town. [17] When the great stream had taken to its new channel, Cyrus ordered his Persian officers to bring up their thousands, horse and foot alike, each detachment drawn up two deep, the allies to follow in their old order. [18] They lined up immediately, and Cyrus made his own bodyguard descend into the dry channel first, to see if the bottom was firm enough for marching. [19] When they said it was, he called a council of all his generals and spoke as follows: