Ctesias declared the cause of the capture to have been the destruction of the city wall by an unexpected rise of the river.

Now, the prophet Nahum, in his announcement of the fate coming on Nineveh, has a very remarkable expression, which seems most naturally to point to some destruction of a portion of the fortifications by means of water.

After relating the steps that would be taken for the defence of the place, he turns to remark on their fruitlessness, and says: "The gates of the rivers are opened, and the palace is dissolved; and Huzzab is led away captive; she is led up, with her maidens, sighing as with the voice of doves, smiting upon their breasts." Now, we have already seen that at the northwest angle of Nineveh there was a sluice or floodgate, intended mainly to keep the water of the Khosrsu, which ordinarily filled the city moat, from flowing off too rapidly into the Tigris, but probably intended also to keep back the water of the Tigris, when that stream rose above its common level.

A sudden and great rise of the Tigris would necessarily endanger this gate, and if it gave way beneath the pressure, a vast torrent of water would rush up the moat along and against the northern wall, which may have been undermined by its force, and have fallen in.

The stream would then pour into the city; and it may perhaps have reached the palace platform, which being made of sun-dried bricks, and probably not cased with stone inside the city, would begin to be "dissolved." Such seems the simplest and best interpretation of this passage, which, though it is not historical, but only prophetical, must be regarded as giving an importance that it would not otherwise have possessed to the statement of Ctesias with regard to the part played by the Tigris in the destruction of Nineveh.
The fall of the city was followed by a division of the spoil between the two principal conquerors.