page_title: Byzantine army
section_title: The army under Diocletian and Constantine
hierarchical_section_title: Byzantine army / History / The army under Diocletian and Constantine
context_page_description: The Byzantine army or East Roman army was the primary military body of the Byzantine armed forces, serving alongside the Byzantine navy. A direct continuation of the Roman army, the East Roman army maintained a similar level of discipline, strategic prowess and organization. It was among the most effective armies of western Eurasia for much of the Middle Ages. Over time the cavalry arm became more prominent in the Byzantine army as the legion system disappeared in the early 7th century. Later reforms reflected some Germanic and Asian influences – rival forces frequently became sources of mercenary units e.g.; Huns, Cumans, Alans and Turks, meeting the Empire's demand for light cavalry mercenaries. Since much of the Byzantine military focused on the strategy and skill of generals utilizing militia troops, heavy infantry were recruited from Frankish and later Varangian mercenaries.
  From the seventh to the 12th centuries, the Byzantine army was among the most powerful and effective military forces in the world – neither Middle Ages Europe nor the fracturing Caliphate could match the strategies and the efficiency of the Byzantine army.
context_section_description: The Eastern Empire dates from the creation of the Tetrarchy ("Quadrumvirate") by the Emperor Diocletian in 293. His plans for succession did not outlive his lifetime, but his reorganization of the army did by centuries. Rather than maintain the traditional infantry-heavy legions, Diocletian reformed it into limitanei ("border") and comitatenses ("field") units.
  There was an expansion of the importance of the cavalry, though the infantry still remained the major component of the Roman armies, in contrast to common belief. In preparation for Justinian's African campaign of 533-534 AD, the army assembled amounted to 10,000-foot soldiers and 5,000 mounted archers and federate lancers.
  The limitanei and ripenses were to occupy the limes, the Roman border fortifications. The field units, by contrast, were to stay well behind the border and move quickly where they were needed, whether for offensive or defensive roles, as well as forming an army against usurpers. The field units were held to high standards and took precedence over Limitanei in pay and provisions.
  Cavalry formed about one-third of the units, but as a result of smaller units, about one-quarter of the Roman armies consisted of cavalry. About half the cavalry consisted of heavy cavalry (including the stablesiani). They were armed with spear or lance and sword and armored in mail. Some had bows, but they were meant for supporting the charge instead of independent skirmishing.
  In the field armies there was a component of some 15% of cataphractarii or clibanarii, heavily armoured cavalry who used shock tactics. The light cavalry (including the scutarii and promoti) featured high amongst the limitanei, being very useful troops on patrol. They included horse archers (Equites Sagittarii). The infantry of the comitatenses was organized in regiments (variously named legiones, auxilia or just numeri) of about 500–1,200 men. They were still the heavy infantry of old, with a spear or sword, shield, body armour and a helmet. But now each regiment was supported by a detachment of light infantry skirmishers.
  If needed, the infantry could take off (some of) their armour to act in a more flexible way as Modares did (according to Zosimus) during the Gothic War of the 370s. The regiments were commanded by a tribunus ("tribune") and brigaded in pairs (cavalry units did, too) under a comes. These brigades probably were tactical and strategic units only, as no traces survive of brigade staff corps.
  On the other hand, little is known of the limitanei. The old legions, cohorts and cavalry alae survived there, and newer units were created (the new legions, or auxilia and vexillationes, amongst the cavalry. The limitanei infantry may have been lighter-equipped than the comitatenses infantry, but there is no evidence whatsoever. They were paid less than the field troops and recruited locally. Consequently, they were of inferior quality. However, they were in the line of fire. They countered most incursions and raids. Thus, it can be assumed they had superior field experience (except in periods of long campaigning for the comitatenses), though that experience did not extend to large battles and sieges.
  The Scholae Palatinae units, which were more properly known as the Schola Protectores Domestici and the "Protective Association of the Royal Escort" (also called the Obsequium), were the personal guard of the Emperor, and were created to replace the Praetorian Guard disbanded by Constantine I.
  Following a major reorganisation of the Roman army during the Emperor Diocletian's reign (284-305 AD) the legions in the third and fourth century bore little resemblance to those of the Republic or earlier Roman empire.  Reduced in numbers to about 1,000 men per legion, these units became static garrison troops, sometimes serving on a part-time militia basis as hereditary limitanei. As such they were separate from the new mobile field army.
caption: Emperor Constantine I.
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