The Roman military service could last between 16 and 26 years. The service for legionaries was 20 years, for auxiliaries 25 years and for those of the fleet between 26 and 28 years.

There were two castra (military camps) with stone walls at Porolissum.

The garrison of the two castra was formed by soldiers recruited from Brittany, Thrace, Syria, Germany, etc.

The Roman soldiers who did not respect the military discipline were harshly punished and could receive even the capital punishment. The death penalty was given even to sentinels who were falling asleep or leaving their post.