In Nahum 2:6–9 Nahum’s vision develops as the attackers break into the city and Nineveh falls.
According to historical accounts Nineveh was conquered by diverting the water of the Tigris River, which ran past Nineveh, into the city.1 As the river gates are opened by the invading army, the city is flooded and either the palace itself is literally washed away or the flood is so devastating that the palace defences are so weakened that all resistance melts away and the palace and the city falls to the Babylonian army.
6 The river gates are opened; the palace melts away;