Dux (title)

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Army leaders of the Comitatenses and Limitanei in the 5th century AD.
The forts of Dux Mogontiacensis in the Notitia Dignitatum .
Coin image of Theodosius I. The emperor held the office of Dux Moesiae primae at a young age (around 373) .
Sesterce of Maximinus Thrax, presumably he held the office of Dux ripae in the province of Mesopotamia around 233

The Dux ( Latin “leader” from ducere “lead”, also “pull”; plural duces ) originated in the Roman Empire and was the official title for the commanders of the border troops ( Limitanei ).

Roman Empire


During the Republic and in the early Principate , dux did not denote a particular rank; this only changed in the course of the 3rd century . In late antiquity, the Duces usually rose from the ranks of the Comitatenses ( tribunate ). When they took their leave, tribunes were also very often discharged from the army with the dignity of a dux. From Valentinian I. the Duces belonged to the newly created rank of the second senatorial rank class, the viri spectabiles . Originally, this title referred to an officer who, in exceptional times of crisis, was given a command that went beyond his actual rank. Often one hears of primi pili as duces legionis or of officers in the senate who are named as duces for land and naval units of a province, an army or individual vexillations . For example, a prefect of the fleet in Misenum was awarded the rank of dux per Africam, Numidiam et Mauretaniam . This gave him a command with extensive freedom of action to fight pirates in the western Mediterranean. These military leaders formed the transition to the Duces of the 4th to 6th centuries.

Since the imperial reforms of Diocletian and Constantine I , in which military and civil administration were separated from one another (see late antiquity ), the dux limitis could be clearly defined as the military commander of a province , especially a border province. Twelve were stationed in the west and thirteen in the east of the empire. One reason for this was probably the increasing unwillingness of Roman citizens to join the army and the subsequent barbarization of the officer corps . It became more and more difficult to find suitable military personnel who would maintain border protection and at the same time bring with them the necessary legal knowledge to cope with the diverse tasks in civil administration. The main reason, however, was probably the emperors' fear of further usurpations. The civil governor ( Praeses ) and the Dux now had to share power over the province and thus became dependent on one another and controlled one another. As a result, the relationship between them was often tense.

In particularly troubled regions such as Isauria , Mauritania and Arabia , however, the division between civil and military administration was not carried out by Diocletian. Due to the constant threat of robber gangs and nomad tribes, the Dux still combined both competencies in his office. The ruler found it more practical to keep the old system. The governors of these inhospitable and poorly profitable provinces would hardly have been able to instigate a revolt against the central government.

In general, however, the Dux was not responsible for civil administration matters. Especially in the east, especially since the time of Justinian , there was again an increasing concentration of power in the hands of the Duces, as the emperor had partially abolished the principle of separation and in some cases even placed the Dux above the governor. A fundamental change in the system of late antiquity did not come into force for the Eastern Empire until the 7th century under Emperor Herakleios , in the course of the expansion of Islam and the transformation of the provinces into themes .


The most important task of the Dux was to secure one or - more rarely - several provinces externally (see Dux Pannoniae Primae et Norici Ripensis ) and internally, for example military action against Christian heretics or "pagans". In addition to its location-bound associations ( Limitanei / Ripenses ) and naval units, since the 5th century a Dux, equipped with the powers of a Comes , has also been able to dispose of mobile units of the field army (Comitatenses) (for example Comes litoris Saxonici per Britanniam ). Perhaps this is an explanation for the fact that in the western Notitia Dignitatum (around 425) a whole series of units appear, which are indicated at the same time in the lists of the Duces and the army masters. In 492 AD the Eastern Emperor Anastasios I also finally subordinated the mobile troops to the Duces. He was supported in this by the members of his administrative staff, officium , who could also be held liable for all actions and orders of their immediate superiors.

The duties of a Dux also included the construction, maintenance and repair of the local fortifications and warships. Larger construction projects on the border sections, however, were directly initiated by the emperor. Occasionally his men even had to go out to catch animals for the elaborate circus games in Rome and Constantinople. The right to grant leave (commeatus) belonged only to the Duces; lower-ranking officers were fined if they acted on their own accord. The Dux also had the right to contact the emperor directly, as there was no explicitly regulated channel of authority. The military justice was in his hands; Until 413, however, the governor or the vicar were still responsible for the soldiers in civil law matters. Only in disputes between civilians and soldiers did the vicar of the diocese take the proceedings if the Dux could not agree on the place of jurisdiction with the governor.

The recruitment and allocation of food were the tasks of the Praetorian Prefecture, since the placement of recruits was seen as an aspect of the tax burden on landowners. The recruits transferred from imperial estates were assigned by the office of Comes rerum privatarum . The Dux had to take them and then assign them to their respective units. The same also applied to the goods in kind delivered by the civil administration. Constantine the Great ordered that the Duces should first personally inspect all newly recruited recruits in order to be able to sort out the unfit immediately. It is unclear whether this was actually implemented in practice. After taking the oath, they were solely responsible to the Dux. He was also allowed to prosecute and try deserters without consulting the civil authorities.

The Dux had to submit regular lists of his material consumption to the civil administration. His officium also had to give an account of the consumption of money and supplies to the praefectus praetorio , the highest civil official, every four months . This enabled at least a rudimentary control and made the military dependent on civil authorities. So the Dux actually had two superiors: the praefectus praetorio and the magister militum . All funds that he needed to maintain the military capabilities and infrastructure of his army had to be approved in advance by the responsible prefecture. In addition, the fees incurred for issuing his certificate of appointment had to be paid to the offices of the prefect and the army master.

Diplomatic assignments had usually not comfortable but to receive the duty, foreign (especially Persian) embassies and to ensure their smooth and safe onward journey to the imperial residence, where he was the Dux, including the imperial courier ( Cursus publicus ) avail could. Otherwise he only had limited rights of use for the latter; In the Eastern Empire, he received a precisely defined number of entitlement certificates each year, which had to last for one year. This should counteract the frequent misuse of the course .

Official titles and ranking

If a Dux commanded the troops of a border province, then his full title was Dux limitis provinciae illius , if he had another command, he was simply referred to as Dux provinciae illius . The name of the official district of a late Roman Dux is comparable to that of a Comes: Most official names go back to the provinces in which a ducat was established, such as the Dux Belgicae secundae or the Dux Mesopotamiae . The Dux Britanniarum was an exception here, it was named after an entire diocese .

In the Roman military hierarchy, the Dux was subordinate to the Comes. Several times, however, the Comes title was also awarded to Duces, which meant an increase in prestige and power, but did not change his original tasks essentially. If he had distinguished himself through special achievements, he also held the title of Comes primi ordinis and was allowed to call himself comes et dux , which raised him above the civil governor ( Praeses ). The comitiva primi ordinis was automatically connected with the command of some particularly important provinces . In this case, the respective incumbent was referred to as comes limitis or comes rei militaris .

Under Constantine I, the title egregius disappears from 326 onwards , while the title perfectissimus is now devalued and used for holders of lower knightly offices. The Dux initially retained the title of vir perfectissimus in the hierarchy of the Roman high aristocracy . In 368 a Dux is first attested as vir clarissimus in an inscription and thus rose to the rank of senator. But not until the late period Valentinian I the rank of the remains vir perfectissimus for a military commander Province ( Dux Valeriae Ripensis ) received. This is attested by the brick stamps of Dux Frigeridus, who was in office in the province of Valeria until 373. During the transition, both titles remained side by side. Only from 386 onwards are all Duces generally referred to as viri clarissimi .

Since Valentinian I , the Dux has belonged to the newly created class of viri spectabiles (= excellence). This rank was a non-hereditary additional predicate of the now hereditary senatorial rank (the so-called Clarissimat) and equated it with a vicarius . The vir spectabilis , however, was dignified under a vir illustris . By an imperial decree, a Dux could also be elevated to an illustris . Towards the end of the 6th century, Duces are sometimes also referred to as magnificus and gloriosus .


For some duces, the amount of their regular wages is also known. The Dux et praeses provinciae Mauritaniae et Caesariensis received in the reign of Valentinian III. fifty capitus , the Dux Libyarium at the time of Justinian I also fifty capitus . They received considerably more benefits than their soldiers, and this probably also applied to the payment of donations .

Ostrogoth Empire

In Theodoric's Ostrogothic empire , the Dux functioned as a largely independent commander of an army. As governors, the Ostrogothic Duces were also responsible for the jurisdiction, but as a rule only over the Gothic part of the population (and in disputes between Goths and Romans). However, unlike their Visigoth relatives, for example, they only held a temporary command. In this way they differed from a Limes commander in the late antique tradition, as he was also represented by the Dux Raetiae under Theodoric .

Byzantine Empire

With the end of the late antique structures in the 7th century in Eastern / Byzantium, the office of dux also disappeared in its previous form. In the Central Byzantine thematic constitution , the dux was now the governor of a ducat , a subordinate military district of the topic , later, after the major topics had been divided into smaller units in the 10th and 11th centuries, a denomination of rank synonymous with the strategist . The office of megas dux (roughly "Grand Duke") was introduced around 1090 and designated the commander-in-chief of the Byzantine fleet . It existed until the fall of Constantinople in 1453. The Byzantine ruling family of the Dukas probably derived their name from the name dux .

Franconian Empire

The Franconian Merovingians took over many late Roman administrative structures and offices and modified them in the course of the 6th century.

In the Franconian Empire , dux was a title for the ruler to combine late Roman civitates or Pagi into one unit, or a larger or important part of the country without such late Roman administrative structures, usually also a newly conquered border area. These parts of the country are also known as ducats and were described geographically (e.g. the Juradukat or Alsace ) or according to population groups (e.g. for the Bavarian region ). Due to the rule over a border area, such a title meant a military function rather than an administrative function, as the Franks rarely intervened in existing forms of administration.

The title was initially not hereditary and not linked to the part of the country itself. The connection and the heredity crystallized only in the course of the centuries, similar to the comites . Unlike in Roman times, the duces (dukes) were ultimately considered to be superior in rank to the comites (counts).

Other meanings

While the term Herzog became established for the title in the German language (and similar things in other Germanic languages), the term was linguistically developed in the countries characterized by the Latin language:

The designation ducat for coins minted in Venice for the first time at the end of the 13th century is also related to the title dux , where the inscription on the reverse gave the name:

Sit tibi Christe datus quem tu regis iste ducatus

"To you, Christ, be this duchy, which you rule, given."


  • Ross Cowan: Imperial Roman Legionary AD 161-284 . Osprey, Oxford 2003, ISBN 1-84176-601-1 , p. 61 ( Warrior 72).
  • Alexander Demandt : The late antiquity. Beck, Munich 2007, ISBN 978-3-406-55993-8 ( Handbook of Classical Studies III, 6).
  • Robert Grosse : Roman military history from Gallienus to the beginning of the Byzantine thematic constitution. Weidmann, Berlin 1920, pp. 152-161 (reprint. Arno Press, New York NY 1975, ISBN 0-405-07083-7 ).
  • Richard Heuberger : The Ostrogoth Raetia . In: Klio . 30, 1937, pp. 77-109.
  • AHM Jones : The Later Roman Empire 284-602. A Social, Economic and Administrative Survey. 4 volumes. Blackwell, Oxford 1964.
  • Gideon Maier: Officials and rulers in Romania Gothica. Comparative studies on the institutions of the East Germanic migration empires. Steiner, Stuttgart 2005, ISBN 3-515-08505-X ( Historia . Individual writings 181), (At the same time: Freiburg (Breisgau), Univ., Diss., 1998).
  • Ralf Scharf : The Dux Mogontiacensis and the Notitia Dignitatum. A study of late antique border defense. de Gruyter, Berlin a. a. 2005, ISBN 3-11-018835-X ( Reallexikon der Germanischen Altertumskunde . Supplementary volumes 48).
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  • Markus Beyeler: Gifts from the emperor. Studies on the chronology, on the recipients and on the objects of the imperial gifts in the 4th century AD , series KLIO / supplements, new series 18, de Gruyter, Berlin 2015, ISBN 978-3-05-005776-7 .
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  • Michael Zerjadtke: The Dux office in late antiquity and the early Middle Ages: The ducatus in the field of tension between Roman influence and its own development . Verlag Walter de Gruyter, Berlin 2018.


  1. Camp leader of a legionary fort. First centurion of the Triarians in the Roman army; since Marius the first centurion of the first cohort and supreme centurion of the legion . He had the eagle ( aquila ) in his care, administered the assets of his legion and was called in as an advisor at meetings of the council of war. After completing his service, he enjoyed special privileges under the emperors.
  2. Ralf Scharf p. 55
  3. Jochen Martin: Late antiquity and migration of the peoples. Oldenbourg science publisher. Munich 2001. ISBN 3-486-49684-0 . P. 73.
  4. Cf. for example Ammianus Marcellinus 21,16,2.
  5. CIL 3, 6159 .
  6. Notitia Dignitatum, IN PARTIBUS OCCIDENTIS, XXXIII.
  7. ^ Maria R.-Alföldi: Gloria Romanorum. Writings on late antiquity. In the Historia series . Individual publications 153. Franz Steiner Verlag, Stuttgart 2001, ISBN 3-515-07918-1 . P. 320 footnote.
  8. Thomas Fischer, 2012, p. 28
  9. ^ Markus Beyeler, p. 236
  10. Eugen Ewig: The Merovingians and the Franconian Empire, 6th edition; Stuttgart 2012. Page 97ff. ISBN 978-3-17-022160-4