Charles Ellicott Commentary Nahum 2:5

"He remembereth his nobles: they stumble in their march; they make haste to the wall thereof, and the mantelet is prepared." — Nahum 2:5 (ASV)

And the defence shall be prepared. —Better, but [there] the storming-shed has been prepared. Here, the surprise and disorder of Nineveh are more plainly portrayed. The Assyrian king thinks of his strongest warriors, but they stumble in their paths in nervous perplexity. Men ran to the city wall, but against it the besiegers had already erected their storming-shed—a procedure that should have been prevented by the discharge of stones and other missiles from the walls. The storming-shed protected the battering-rams.

Concerning the representations of these preserved in the monuments of Nineveh, Professor Rawlinson writes as follows: “All of them were covered with a framework, which was of osier wood, felt, or skins, for the better protection of those who worked the implement.... Some appear to have been stationary, others provided with wheels.... Again, sometimes combined with the ram and its framework was a movable tower containing soldiers, who simultaneously fought the enemy on a level and protected the engine from their attacks (Ancient Monarchies, i. 470).”