Histories

So when Darius assaulted the whole circuit of the walls, according to the agreed plan, then Zopyrus' treason was fully revealed. For while the townsmen were on the wall defending it against Darius' assault, he opened the gates called Cissian and Belian, and let the Persians inside the walls.

Those Babylonians who saw what he did fled to the temple of that Zeus whom they call Belus; those who had not seen it remained in position, until they too discovered how they had been betrayed.