Comitatenses is the Latin plural of comitatensis, originally the adjective derived from comitatus

Comitatus

Comitatus may refer to:* Comes, a Latin word with similar meaning* Comitatenses, the Roman late Imperial mobile army...

('company, party, suite'; in this military context it came to the novel meaning of 'the field army'), itself rooting in Comes

Comes

Comes , plural comites , is the Latin word for companion, either individually or as a member of a collective known as comitatus, especially the suite of a magnate, in some cases large and/or formal enough to have a specific name, such as a cohors amicorum. The word comes derives from com- "with" +...

('companion', but hence specific historical meanings, military and civilian).

However, historically it became the accepted (substantivated) name for those Roman imperial troops

Roman army

The Roman army is the generic term for the terrestrial armed forces deployed by the kingdom of Rome , the Roman Republic , the Roman Empire and its successor, the Byzantine empire...

 (legion

Roman legion

A Roman legion normally indicates the basic ancient Roman army unit recruited specifically from Roman citizens. The organization of legions varied greatly over time but they were typically composed of perhaps 5,000 soldiers, divided into maniples and later into "cohorts"...

s and auxiliary) which were not merely garrisoned at a limes

Limes

A limes was a border defense or delimiting system of Ancient Rome. It marked the boundaries of the Roman Empire.The Latin noun limes had a number of different meanings: a path or balk delimiting fields, a boundary line or marker, any road or path, any channel, such as a stream channel, or any...

 (fortified border, on the Rhine and Danube in Europe and near Persia and the desert tribes elsewhere) — the limitanei

Limitanei

The limitanei, meaning "the soldiers in frontier districts" The limitanei, meaning "the soldiers in frontier districts" The limitanei, meaning "the soldiers in frontier districts" (from the Latin phrase limes, denoting the military districts of the frontier provinces established in the late third...

or ripenses, i.e. 'along the shores' — but more mobile line troops; furthermore there were second line troops, named pseudocomitatenses, former limitanei attached to the comitatus; palatini

Palatini (Roman military)

The palatini were elite regiments of the Late Roman army mostly attached to the comitatus praesentales, or imperial escort armies...

, elite ("palace") units typically assigned to magistri militum

Magister militum

Magister militum was a top-level military command used in the later Roman Empire, dating from the reign of Constantine. Used alone, the term referred to the senior military officer of the Empire...

; and the scholae palatinae

Scholae Palatinae

The Scholae Palatinae , were an elite military guard unit, usually ascribed to the Roman Emperor Constantine the Great as a replacement for the equites singulares Augusti, the cavalry arm of the Praetorian Guard...

of actual palace guards, notably under the magister officiorum

Magister officiorum

The magister officiorum was one of the most senior administrative officials in the late Roman Empire and the early centuries of the Byzantine Empire...

, a major court official of the Late Empire.

List of comitatenses units

Among the comitatenses units listed by Notitia Dignitatum

Notitia Dignitatum

The Notitia Dignitatum is a unique document of the Roman imperial chanceries. One of the very few surviving documents of Roman government, it details the administrative organisation of the eastern and western empires, listing several thousand offices from the imperial court down to the provincial...

there are:

under Magister Peditum

• 1. Undecimani.
  2. Secundani Italiciani (Legio II Italica
     Legio II Italica
     Legio secunda Italica , was a Roman legion levied by emperor Marcus Aurelius in 165 together with I Italica at a time when the Roman Empire was fighting both in Germania and in Parthia. There are still records of the II Italica in Noricum in the beginning of the 5th century...
     
     , Africa);
  3. Tertiani Italica (Legio III Italica
     Legio III Italica
     Legio tertia Italica was a Roman legion levied by Marcus Aurelius around 165, for his campaign against the Marcomanni tribe. The cognomen Italica suggests that recruits were originally from Italy. The legion was still active in Raetia and other provinces in the early 5th century Legio tertia...
     
     , Illyricum);
  4. Tertia Herculea, Illyricum;
  5. Secunda Britannica, Gallias;
  6. Tertia Iulia Alpina, Italia;
  7. Prima Flavia Pacis, Africa;
  8. Secunda Flavia Virtutis
     Legio II Flavia Virtutis
     Legio II Flavia Virtutis was a comitatensis Roman legion, levied by Emperor Constantius II , together with I Flavia Pacis and III Flavia Salutis....
     
     , Africa;
  9. Tertia Flavia Salutis, Africa;
  10. Secunda Flavia Constantiniana, Africa Tingitania;
  11. Tertioaugustani (Legio III Augusta
      Legio III Augusta
      Legio tertia Augusta was raised in the year 43 BCE most likely by the consul Gaius Vibius Pansa and the emperor Augustus who served the Roman Empire in North Africa until at least the late 4th century CE. It is possible that it fought in the battle of Philippi against the murderers of Caesar...
      
      );

under the Magister Militum per Orientem

• 1. Quinta Macedonica (Legio V Macedonica
     Legio V Macedonica
     Legio quinta Macedonica was a Roman legion. It was probably originally levied by consul Gaius Vibius Pansa Caetronianus and Octavian in 43 BC, and it was stationed in Moesia at least until 5th century. Its symbol was the bull, but the eagle was used as well...
     
     );
  2. Septima gemina (Legio VII Gemina
     Legio VII Gemina
     Legio septima Gemina was a Roman legion; its full name was Legio VII Gemina Felix. VII Gemina dates back to the Year of the four emperors , when the governor of Hispania Tarraconensis, Galba, levied a legion to march on Rome...
     
     );
  3. Decima gemina (Legio X Gemina
     Legio X Gemina
     Legio decima Gemina , was one of the four legions used by Julius Caesar in 58 BC, for his invasion of Gaul. There are still records of the X Gemina in Vienna in the beginning of the 5th century. The legion symbol was a bull...
     
     );
  4. Prima Flavia Constantia;
  5. Secunda Flavia Constantia Thebaeorum
     Legio II Flavia Constantia
     The Legio II Flavia Constantia was a comitatensis Roman legion, created by Diocletian, probably in the year 296 or 297....
     
     ;
  6. Secunda Felix Valentis Thebaeorum;
  7. Prima Flavia Theodosiana;

under the Magister Militum per Thracias

• 1. Prima Maximiana Thebaeorum
     Legio I Maximiana
     The Legio I Maximiana was a comitatensis Roman legion, probably created in the year 296 or 297 by the Emperor Diocletian....
     
     ;
  2. Tertia Diocletiana Thebaeorum
     Legio III Diocletiana
     Legio III Diocletiana was a comitatensis Roman legion, levied in 296 by Diocletian, from whom the legion took its name.The aim of this legion was to guard the newly re-organized province of Aegyptus, being based in Alexandria...
     
     ;
  3. Tertiodecimani (Legio XIII Gemina
     Legio XIII Gemina
     Legio tertia decima Gemina was one of the most prominent Roman legions. It was one of Julius Caesar's key units in Gaul and in the civil war, and was the legion with which he famously crossed the Rubicon on January 10, 49 BC. The legion appears to have still been in existence in the fifth century...
     
     ?);
  4. Quartodecimani (Legio XIV Gemina Martia Victrix
     Legio XIV Gemina
     Legio quarta decima Gemina was a legion of the Roman Empire, levied by Julius Caesar in late 58 B.C. The cognomen Gemina suggests that the legion resulted from fusion of two previous ones, one of them being the Fourteenth legion that fought in the Battle of Alesia, the other being the Martia ...
     
     ?);
  5. Prima Flavia gemina;
  6. Secunda Flavia gemina.

External links

• http://www.durolitum.co.uk/ - Britannia - Late Roman reenactment group. Biggest, most well known and oldest late roman reenactment group in Britain