List of Roman legions

This is a list of Roman legions, including key facts about each legion, primarily focusing on Principate (early Empire, 27 BC - 284 AD) legions, for which there exists substantial literary, epigraphic and archaeological evidence.

Until the 1st century BC, legions were temporary citizen levies, raised for specific campaigns and disbanded after them. By the early 1st century BC, legions were mixed volunteer/conscript units. Legions became standing units, which could remain intact long after a particular campaign was finished. Large numbers of new legions were raised by rival warlords for the civil wars of the period 49-31 BC.

However, when Augustus became sole ruler in 31 BC, he disbanded about half of the over 50 legions then in existence. The remaining 28 legions became the core of the early Imperial army of the Principate (27 BC – 284 AD), most lasting over three centuries. Augustus and his immediate successors transformed legions into permanent units, staffed by entirely career soldiers on standard 25-year terms.

During the Dominate (late Empire, 284–476), legions were also professional, but are little understood due to scarcity of evidence compared to the Principate. What is clear is that late legions were radically different in size, structure and tactical role from their predecessors, despite several retaining early period names. This was the result of the military reforms of Emperors Diocletian and Constantine I, and of further developments during the 4th century.

The legions were identified by Roman numerals, though the spelling sometimes differed from the modern "standard". For example, in addition to the spellings "IV", "IX", "XIV", "XVIII" and "XIX", the respective spellings "IIII", "VIIII", "XIIII", "XIIX" and "XVIIII" were commonly used.

Late Republican legions
Until the Marian reforms of 107 BC, the Republican legions were formed by compulsory levy of Roman citizens (who met a minimum property qualification) and raised whenever it was necessary. Usually they were authorized by the Roman Senate, and were later disbanded.

Gaius Marius' reforms transformed legions into standing units, which could remain in being for several years, or even decades. This became necessary to garrison the Republic's now far-flung territories. Legionaries started large-scale recruiting of volunteer soldiers enlisted for a minimum term of six years and a fixed salary, although conscription was still practiced. The property requirements abolished by Marius, so that the bulk of recruits were henceforth from the landless Citizens, who would be most attracted to the paid employment and Land offered after their service.

In the last century of the Republic, proconsuls governing frontier provinces became increasingly powerful. Their command of standing legions in distant and arduous military campaigns resulted in the allegiance of those units transferring from the Roman state to themselves. These imperatores (lit: victorious generals, from the title imperator they were hailed with by their troops) frequently fell out with each other and started civil wars to seize control of the state. e.g. Sulla, Caesar, Pompey, Crassus, Mark Antony and Octavian (later Augustus, the first Emperor himself). In this context, the imperatores raised many legions that were not authorised by the Senate, sometimes having to use their own resources. As civil wars were resolved, many of these "private" units would be disbanded, only for more to be raised to fight the next civil war. By the time Augustus emerged as sole ruler of Rome in 31BC, over 50 legions were in existence, many of which were disbanded.

The legions included in the following list had a long enough history to be somehow remarkable. Most of them were levied by Julius Caesar and later included into Octavian's army, some of them were levied by Mark Antony.


 * Legio I Germanica (Germanic): 48 BC–70 (Batavian rebellion), Julius Caesar
 * Legio II Sabina (Sabine): 43 BC to circa 9 AD, early name of the Legio II Augusta
 * Legio III Cyrenaica (from Cyrenaica): probably around 36 BC to (at least) 5th century, Mark Antony
 * Legio III Gallica (from Gallia): around 49 BC to at least early 4th century, Julius Caesar (emblem: bull)
 * Legio IV Macedonica (Macedonian): 48 BC–70 (disbanded by Vespasian), Julius Caesar (emblem: bull, capricorn)
 * Legio IV Scythica (from Scythia): around 42 BC to at least early 5th century, Mark Antony (emblem: capricorn)
 * Legio V Alaudae (Larks): 52 BC–70 (destroyed in the Batavian rebellion), Julius Caesar (emblem: elephant)
 * Legio VI Ferrata (Ironclad): 52 BC to after 250, Julius Caesar (emblem: bull, wolf and Romulus and Remus); twin legion of Legio VI Victrix
 * Legio VI Victrix (Victorious): 41 BC to after 402, Octavian (emblem: bull)
 * Legio VII Claudia Pia Fidelis: 51 BC–44 BC, Julius Caesar; disbanded and re-formed by Vespasian as Legio VII Gemina
 * Legio VIII Augusta: 59 BC–48 BC, Julius Caesar, disbanded and re-enlisted by Augustus as Legio VIII Augusta
 * Legio IX Hispana Triumphalis (Triumphant): 59 BC–48 BC, Julius Caesar, disbanded and re-enlisted by Augustus as Legio IX Hispana
 * Legio X Fretensis (of the sea strait), also known as X Equestris (Mounted): before 58 BC–45 BC, Julius Caesar's personal legion.
 * Legio X: another name of X Equestris.
 * Legio X Equestris levied by Augustus in 41/40 BC
 * Legio XI: 58 BC–45 BC, Julius Caesar (emblem: Neptune), disbanded, reconstituted by Augustus
 * Legio XII Victrix (Victorious): 57 BC–45, Julius Caesar
 * Legio XII Antiqua (Ancient): reconstituted by Lepidus in 43 BC, named by Mark Antony, included in Augustus army as Legio XII Fulminata
 * Legio XIII Gemina: 57 BC–45 BC: Julius Caesar, later (41 BC) reconstituted as Legio XIII Gemina by Augustus
 * Legio XVIII Libyca (from Libya): disbanded 31 BC, Mark Antony
 * Legio XXX Classica (Naval): 48 BC–41 BC, Julius Caesar

Early Empire legions


Code for Roman provinces in the table:


 * AEG Aegyptus (Egypt)
 * AFR Africa (Tunisia/Western Libya)
 * AQ Aquitania (SW France)
 * AR Arabia Petraea (Jordan/Sinai)
 * BRIT Britannia (England/Wales)
 * CAP Cappadocia (Central/Eastern Turkey)
 * DC Dacia (Romania/Serbia)
 * DLM Dalmatia (Croatia/Bosnia/Serbia)
 * GAL Galatia (Central Turkey)
 * GI Germania Inferior (Netherlands/Rhineland)
 * GS Germania Superior (Alsace-Lorraine/Rhineland)
 * HISP Hispania Tarraconensis (Central Spain)
 * IT Italia (Italy)
 * JUD Judaea (Palestine)
 * MAUR Mauretania (Western Maghreb)
 * MCD Macedonia (Southern Balkans)
 * MI Moesia Inferior (Romania/Bulgaria)
 * MS Moesia Superior (Serbia)
 * NR Noricum (Austria)
 * PAN Pannonia (Croatia/Slovenia)
 * RT Raetia (Switzerland)
 * SYR Syria (Syria/Lebanon)

Legend
The numbering of the legions is confusing, since several legions shared the same number with others. Augustus numbered the legions he founded himself from I, but also inherited numbers from his predecessors. Each emperor normally numbered the legions he raised himself starting from I. However, even this practice was not consistently followed. For example, Vespasian kept the same numbers as before for legions he raised from disbanded units. Trajan's first legion was numbered XXX because there were 29 other legions in existence at the time it was raised; but the second Trajanic legion was given the sequential number II. XVII, XVIII and XIX, the numbers of the legions annihilated in the Teutoburg Forest, were never used again. (These three legions are without titles, suggesting that in disgrace their titles may have been deliberately forgotten or left unmentioned.) As a result of this somewhat chaotic evolution, the legion's title became necessary to distinguish between legions with the same number.
 * Legion number and title

Legions often carried several titles, awarded after successive campaigns, normally by the ruling emperor e.g. XII Fulminata was also awarded: paterna (fatherly), victrix (victorious), antiqua (venerable), certa constans (reliable, steadfast) and Galliena (Gallienus '). Pia fidelis (loyal and faithful), fidelis constans and others were titles awarded to several legions, sometimes several times to the same legion. Only the most established, commonly used titles are displayed on this table.

The geographical titles indicate (a) the country a legion was originally recruited e.g. Italica = from Italy or (b) peoples the legion has vanquished e.g.Parthica = victorious over the Parthians Legions bearing the personal name of an emperor, or of his gens (clan) (e.g. Augusta, Flavia) were either founded by that Emperor or awarded the name as a mark of special favour.

The title GEMINA means that two diminished legions have been combined to make one new one.

This shows the castra (base) where the legion spent the longest period during the Principate. Legions often shared the same base with other legions. Detachments of legions were often seconded for lengthy periods to other bases and provinces, as operational needs demanded.
 * Main legionary base

Legions often sported more than one emblem at the same time, and occasionally changed them. Legions raised by Caesar mostly carried a bull emblem originally; those of Augustus mostly a Capricorn
 * Emblem

For legions that are documented into the 4th century and beyond, we do not know when or how they were terminated. For legions disappearing from the record before 284, the reason (certain or likely) is given as: XX = annihilated in battle DD = disbanded in disgrace UF = unknown fate
 * Date disbanded

Indicates the bases (castra) and/or provinces where the legion was based during its history, with dates.
 * Castra legionaria

Contains points of note, including explanation of titles and details of a legion's fate.
 * Notes

Province names and borders are assumed throughout the Principate period as at 107 AD, during the rule of Trajan, and after the annexation of Dacia and Arabia Petraea. The map above shows provinces at the end of Trajan's reign, 117 AD. They are the same as in 107, except that Armenia and Mesopotamia have been annexed (they were abandoned soon after Trajan's death); and Pannonia has been split into two (the split occurred c. 107). In reality provincial borders were modified several times during the period 30 BC-284 AD: this explains any discrepancy with other sources, as to a legion's location at a particular date

Late Empire legions
Diocletian reorganized the Roman army, in order to better counter the threat of the Germanic peoples of northern Europe as well as that of the Persians from the East. The army was formed by border and field units.

The border (limitanei) units were to occupy the limes, the structured border fortifications, and were formed by professional soldiers with an inferior training.

The field units were to stay well behind the border, and to move quickly where they were needed, with both offensive and defensive roles. Field units were formed by elite soldiers with high-level training and weapons. They were further divided into:
 * 1) Scholae: the personal guard of the Emperor, created by Constantine I to replace the Praetorian Guard;
 * 2) Palatinae: "palace troops" were the highest ranked units, created by Constantine I after he disbanded the Praetorian Guard, it was comprised originally of former guardsmen;
 * 3) Comitatenses: regular field units, some were newly formed, others were descended from Early-Empire legions;
 * 4) Pseudocomitatenses: these were limitanei units diverted into the field army and often kept there; some Early Empire legions became pseudocomitatenses units.

These units usually numbered between 300 and 2000 soldiers and some of them kept their original numbering schemes. The primary source for the legions of this era is the Notitia Dignitatum, a late 4th-century document containing all the civil and military offices of both halves of the Roman Empire (revised in ca. 420 for the Western Empire).


 * Legio I
 * I Flavia Constantia (reliable Flavian): comitatensis unit under the command of the Magister militum per Orientis
 * I Flavia Gallicana Constantia (reliable Flavian legion from Gallia): pseudocomitatensis under the command of the Magister Peditum per Gallias
 * I Flavia Martis (Flavian legion devoted to Mars): pseudocomitatensis
 * I Flavia Pacis (Flavian legion of peace): comitatensis under the command of the Magister Peditum
 * I Flavia Theodosiana: comitatensis
 * I Illyricorum (of the Illyrians): stationed at the Camp of Diocletian in Palmyra
 * I Iovia (devoted to Jupiter): levied by Diocletian, stationed in Scythia Minor
 * I Isaura Sagittaria (archers from Isauria): pseudocomitatensis under the command of the Magister militum per Orientis
 * I Iulia Alpina: pseudocomitatensis under the command of the Magister Peditum in Italy
 * I Martia possibly based near modern Kaiseraugst
 * I Maximiana Thaebanorum (the Thebans of Maximianus): comitatensis unit stationed near Thebes, Egypt, and probably fighting in the battle of Adrianople
 * I Noricorum (of the Noricans): stationed in Noricum
 * I Pontica


 * Legio II
 * II Britannica: comitatensis under Magister Peditum
 * II Flavia Constantia: comitatensis under the command of the Magister Peditum
 * II Flavia Virtutis: comitatensis under the command of the Magister Peditum
 * II Herculia (devoted to Hercules): levied by Diocletian, stationed in Scythia Minor
 * II Isaura
 * II Iulia Alpina: pseudocomitatensis under the command of the Magister Peditum, in Comes Illyricum command
 * II Felix Valentis Thebaeorum: comitatensis


 * Legio III
 * III Diocletiana
 * III Flavia Salutis: comitatensis under the command of the Magister Peditum
 * III Herculea: comitatensis under the command of the Comes Illyricum
 * III Isaura
 * III Iulia Alpina: comitatensis under the command of the Magister Peditum command in Italy


 * Legio IV
 * IV Italica
 * IV Martia
 * IV Parthica


 * Legio V
 * V Iovia (maybe the Jovians)
 * V Parthica


 * Legio VI
 * VI Gemella
 * VI Gallicana
 * VI Herculia (maybe the Herculians)
 * VI Hispana
 * VI Parthica


 * Legio XII
 * XII Victrix