\paperw3990 \margr0\margl0 \plain \fs20 \f1 \fs22 The army also included the soldiers of the Praetorian Guard, the city militia, and the vigiles, who were responsible f
or maintaining public order in the city and protecting it against fire. Nor should we forget the slaves and foreigners who did twenty-six years of service on warships. In the third century the Roman military organization went into progressive decline. Th
e army was no longer able to hold back the barbarians on the Empire's vast borders. The mighty walls built around Rome by Aurelian (270-5) proved incapable of preventing the city from being conquered by Genseric, king of the Vandals (455), after over eig
