 In order to do this, the Carolingians used a combination of Late Roman military organization along with the incremental changes that occurred between the fifth and eighth centuries.Because of the defensive strategy the Romans had implemented during the Late Empire, the population had become militarized and were thus available for military use.The existence of the remaining Roman infrastructure that could be used for military purposes, such as roads, strongholds and fortified cities meant that the reformed strategies of the Late Romans would still be relevant.