The actual effectiveness of the wall is disputable, given the relatively small size of the city's garrison. The entire combined strength of the Praetorian Guard, "cohortes urbanae", and "vigiles" of Rome was only about 25,000 men – far too few to defend the circuit adequately. However, the military intention of the wall was not to withstand prolonged siege warfare; it was not common for the barbarian armies to besiege cities, as they were insufficiently equipped and provisioned for such a task. Instead, they carried out hit-and-run raids against ill-defended targets. The wall was a deterrent against such tactics.