Limitanei The limitanei or ripenses meaning respectively " " the soldiers in frontier districts " " ( from the Latin phrase limes , meaning a military district of a frontier province ) or " " the soldiers on the riverbank " " ( from the Rhine and Danube ) , were an important part of the late Roman and early Byzantine army after the reorganizations of the late 3rd and early 4th centuries . The limitanei , unlike the comitatenses , palatini , and scolae , garrisoned fortifications along the borders of the Roman Empire and were not normally expected to fight far from their fortifications . The limitanei were lower - status and lower - paid than the comitatenses and palatini , and the status distinction between scolae , palatini , comitatenses , and limitanei had largely replaced the older distinction between praetorians , legionaries , and auxiliaries . The limitanei and palatini both included legionary units alongside auxiliary units . The nature of the limitanei changed considerably between their introduction in the 3rd or 4th century and their disappearance in the 6th or 7th century . In the 4th century , the limitanei were professional soldiers , and included both infantry and cavalry as well as river flotillas , but after the 5th century they were part - time soldiers , and after the 6th century they were unpaid militia . The role of the limitanei remains somewhat uncertain . Hugh Elton and Warren Treadgold suggest that , besides garrisoning fortifications along the frontier , they operated as border guards and customs police and to prevent small - scale raids . They may have driven off medium - scale attacks without the support of the field armies . Edward Luttwak saw their role as a key part in a strategy of defence - in - depth in combination with the provincial field armies Origins and History . In the early 3rd century , the Roman military was organized into several provincial armies under the command of the provincial governors , a smaller reserve under the command of the emperor , guard units such as the Praetorian Guard , and the urban cohorts . Field armies were temporary formations , usually composed of the reserve and / or of detachments drawn from the provincial armies . In the later 3rd century , due to the frequent wars , field armies could remain together for several years , under the direct command of the emperor , and would require their own recruitment systems . By the mid 4th century , the Roman military was divided into frontier armies under the command of the provincial duces and permanent field armies under the command of the emperor , the magistri peditum , magistri equitum , or comites . The frontier armies would patrol the borders and oppose small - scale raids . They may have driven off medium - scale attacks without the support of the field armies . The frontier armies would later be known as limitanei or ripenses . The field armies would respond to larger - scale attacks , would fight against rival emperors , and would conduct any large - scale attacks into neighboring countries . The field armies would later be known as comitatenses or palatini . The first known written reference to " ripenses " was in 325 and the first to " limitanei " was not until 363 . Historians disagree on whether the emperor Diocletian , or one of his successors , such as Constantine I , split the Roman military into frontier armies and field armies . Theodor Mommsen , H . M . D . Parker , and more recently , Warren Treadgold and David S . Potter attribute the reorganization to Diocletian . E . C . Nischer , D . van Berchem , and more recently , M . C . Bishop and J . C . M . Coulston attribute mainly an expansion to Diocletian , and the reorganization to Constantine I and his successors . Karl Strobel sees the reorganization as the culmination of trends going back well into the 3rd century , with Diocletian strengthening both the frontier and field armies . The division of the Roman Empire , the collapse of its western portion , and the formation of the successor states means that the limitanei may have developed differently in the east and the west , or even in different regions of the west . In the east , the emperor Justinian cancelled their pay . After this , the eastern limitanei were no longer professional soldiers , but continued to exist as militia through the Persian Wars and the Arab Conquest . The Arabic ajnad of Palestine , Jordan , Damascus , and Homs , may represent continuations of the commands of Palaestina , Arabia , Phoeniciae , and Syria . In the west , the collapse of the empire cut off regular pay . Peter Heather notes an incident in the Life of St . Severinus , in Noricum in the 460s , where raiders had intercepted and cut down limitanei who were bringing their pay to the rest of their unit . Organization . The limitanei represented the largest part of the late Roman Army . The eastern portion of the Notitia Dignitatum , from about 395 , may count some 195 , 500 personnel in the frontier armies not counting the river flotillas , 104 , 000 in the field armies not counting the fleets , and 3 , 500 in the palace guard . The western portion , from about 420 , is harder to work with , because it has been unevenly edited , it omits some frontier provinces , and it includes British provinces which were probably lost to the Empire . The size of the army , and therefore of the limitanei , remains controversial . A . H . M . Jones and Warren Treadgold argue that the late Roman army was significantly larger than earlier Roman armies , and Treadgold estimates they had up to 645 , 000 troops . Karl Strobel denies this , and Strobel estimates that the late Roman army had some 435 , 000 troops in the time of Diocletian and 450 , 000 in the time of Constantine I . The limitanei were usually under the command of the duces of their respective provinces . There were some exceptions , with comites commanding units of limitanei , and with duces commanding units from two or more provinces . The units of the limitanei included legiones of infantry , often divided between two bases and sometimes divided among more , numeri , milites , and cohortes of infantry , as well as vexillationes , equites , cunei , and alae of cavalry . The size of the legions is unclear . A . H . M . Jones suggested that they could have as many as 3 , 000 troops , because they are often listed with 10 cohorts , and because they are sometimes divided among many bases . Warren Treadgold suggests that the legions probably had about 1 , 000 troops and the other units probably had about 500 troops each . The different titles of numeri , milites , and cohorts , or vexillationes , equites , cunei , and alae , probably did not correspond with different structures or roles , although according to Pat Southern and Karen Dixon , the " legiones " , " auxilia " , and " cunei " of the border armies were part of the " limitanei " , but higher - status than the older " cohortes " and " alae " in the same armies . Warren Treadgold estimates that 50 . 1 % of the limitanei were infantry and 49 . 9 % cavalry , not counting river flotillas . Roles . The role of the limitanei remains somewhat uncertain . Neither Vegetius , writing in the late 4th or early 5th century , nor Mauricius , writing in the late 6th century , discuss the limitanei in their military manuals . This is understandable . Vegetius called for the revival of earlier Roman practices , from before the organization of the limitanei , and Mauricius wrote after the decline of the limitanei . Hugh Elton and Warren Treadgold suggest that , besides garrisoning fortifications along the frontier , they operated as border guards and customs police and to prevent small - scale raids . Hugh Elton describes their roles as " policing the border , gathering intelligence , and stopping raids . " They may have driven off medium - scale attacks without the support of the field armies . Edward Luttwak saw their role as a key part in a strategy of defence - in - depth , manning a range of defences from forts to walled towns in a deep defensive zone . These defences would deny routes to the enemy , securing food stocks and , in arid areas , water supplies both to restrict attackers and facilitate counter attack by provincial field armies Because units of limitanei operated in one area , had their own camps , and often recruited from the same area , they tended to maintain better relations with the locals than the comitatenses and palatini , who would often be transferred to other areas , and were often quartered in civilian homes . They were light troops and served as a policing force to patrol Rome ' s distant , far - flung border regions and when necessary , to delay advancing enemy forces until counter - attacks could be arranged . They worked in conjunction with the " comitatenses " . Pseudocomitatenses . The relationship between the limitanei , of the border armies , and the pseudocomitatenses , the lowest - ranking units of the field armies , remains unclear . Theodor Mommsen proposed that the pseudocomitatenses were former units of limitanei incorporated into the mobile field armies , and most authors since have followed his theory . E . C . Nischer proposed the alternate theory that the pseudocomitatenses were positional garrison units which were independent of the border armies and thus placed under the same command as the field armies . Farmer - Soldiers ? In the past historians have suggested that the limitanei were organized as units of part - time farmer - soldiers . In this view , the limitanei were used in stationary roles along the frontier and were granted plots of land to cultivate , which essentially turned them into part time soldiers / farmers . It was usually assumed that over time the limitanei settled down more permanently in their posts and became farmers and land owners as well as soldiers ; raising families and earning a living from agricultural means rather than purely military service . It is now more generally assumed that there is no good evidence for this . The current consensus seems to be that the limitanei were organized as units of professional soldiers , but they gradually became part - time soldiers and eventually an unpaid militia , relying on other professions including farming for income . Why this new class of soldiers developed is disputed by historians . According to Azar Gat , many scholars believe that empires stationed these soldiers on the outskirts of empires as a first line of defense against raiding barbarians tribes . As the soldier profession is often not productive ( prolonged periods of training with only occasional conflict ) , empires had long resorted to this principle of " military colonists . " Thus , the late Roman empire adopted the system of limitanei ( frontier - colonist - soldier ) for economic reasons . By employing soldiers in this way , Rome was able to capitalize on their knowledge of warfare as well benefit from the agriculture produced by limitanei . Edward Luttwak , however , sees the change as due a strategic shift away from a firmly held frontier ( " preclusive defence " ) to a less firmly held frontier zone backed with mobile forces ( " defence - in - depth " ) as responsible for the change , though again referencing parallels of military colonists at other times in history . Equipment . M . C . Bishop and J . C . M . Coulston , in a major work on Roman military equipment , do not distinguish that of the limitanei from that of the comitatenses and palatini . It is doubtful whether there were any universal differences between the equipment of the limitanei and of the other forces . The late Roman empire had centralized fabricae , introduced by Diocletian , to provide arms and armor for the army . The 4th century limitanei included both light and heavy infantry , as well as light and heavy cavalry , and river flotillas . Fortifications . The limitanei garrisoned fortifications along the borders of the Roman empire . Hugh Elton divides these into four categories : " garrison forts , detachment forts , watchtowers , and fortified landing places . " These fortifications could be organized into lines along rivers , such as the Rhine and Danube , or at times part of the Euphrates , along fortified walls such as Hadrian ' s Wall , or along otherwise unfortified roads such as the Strata Diocletiana . Garrison forts are those at or near the towns along the frontiers , as well as other forts , garrisoned by independent units of limitanei . Detachment forts are those too small for independent units , garrisoned by detachments from the nearest garrison fort . Fortified landing places are those on the opposite side of riverine borders . Both Diocletian and Constantine I reinforced the frontier fortifications . The fort of Deutz / Divitia , an important bridgehead on the east bank of the Rhine , was built in this period . Generally speaking there were more and smaller forts along the late Roman border than along the earlier Roman imperial borders . This has been interpreted as evidence that units were smaller than before , that units were divided among multiple forts , or both . Effectiveness . The effectiveness of the limitanei , as units , and as part of the larger system , remains controversial . The soldiers of the frontier armies were paid less than their counterparts in the field armies . However , this does not imply that the field armies always hired the most promising recruits ; some may have preferred to stay close to home rather than to join units which could be deployed anywhere else . The soldiers of the frontier armies are often supposed to have been part - time farmer - soldiers without the same degree of training as the soldiers of the field armies ; however , they were originally full - time soldiers . Although these military reforms brought about a more effective defensive army than the previous arrangement had , it did have its pitfalls . Constantine I was criticised for allowing what were perceived as " second - class " infantry , often recruited from non - Roman backgrounds , to be given the responsibility of watching over Rome ' s most troublesome regions . The elite Comitatenses and Scholae Palatinae ( the personal bodyguards of the late Roman Emperors such as Constantine I ) resented being reduced to trivial home guard duties and acting more similarly to an urban police force until such a time that a serious enough threat presented itself at a nearby border , when they were called upon for duty . They are historically significant in that their appearance , as part of a plan of military reforms enacted in the late 3rd century , was able to extend the life of the Roman Empire by pushing back the great barbarian invasion s of late antiquity . The quality of these border troops declined because the limitanei had to live in poor conditions in impoverished and isolated towns , unlike their well - off counterparts the comitatenses , who were typically assigned to more urban and prosperous areas of the empire . This affected the discipline and morale of the late Roman army . The limitanei were nonetheless a fairly well equipped and trained , force of infantry for their time , especially in relation to other standing armies of the day fielded by Rome ' s Germanic , Celtic , Iranian , and Eastern neighbours , collectively referred to as Barbarians by the Romans themselves . It can be surmised due in part to these reforms , that the Roman Empire continued to live on for another 140 years after the end of Constantine ' s reign , in the face of numerous migrations and invasions from northern and eastern , nomadic peoples such as the Huns , Goths , Vandals , Ostrogoths , Sarmatians , Alans , Burgundians , Saxons and Franks , which continually weakened the Empire until its eventual collapse in 476 AD .