The Persians were thus enabled to extend their mounds to the ramparts and scale the battlements of the city .
Ultimately , one of the improvised towers of the Romans collapsed under the repeated shocks of the Persian missile - engines .
The Persian were thus enabled to extend Persian 's mounds to the ramparts and scale the battlements of the city .
Ultimately , one of the improvised towers of the Romans collapsed under the repeated shocks of the Persian missile - engines .