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The Roman legions

Legionary standard (of XXX Ulpia Traiana reenactment group). Photo Jona Lendering.

A Roman legion was an infantry unit consisting of heavily armed soldiers, equiped with shields, armor, helmets, spears and swords. In the early republic, the strength of a legion was about 3,000 men; there were 4,800 legionaries in the days of Julius Caesar; the twenty-five legions that defended the empire during the reign of Augustus counted more than 5,000 soldiers. They were the backbone of the Roman army, supported by auxiliary troops. Although in the third century, large cavalry units gradually superseded the legions as Rome's most important force, many of them are attested in the fourth and early fifth centuries.

On this site, you will find an alphabetical and chronological catalogue of the imperial legions. An overview of the armies in certain provinces is here.

Geographical overview

Related:
RomanArmy.Com

Ancient-Warfare.com, the online home of Ancient Warfare magazine

Reconstruction of a Roman legionary (Rheinisches
Landesmuseum, Bonn)

Alphabetical catalogue

The following table catalogue contains only the legions that served under the early empire. Units in italics were part of the army of the emperor Augustus.

I Adiutrix	III Parthica	XII Fulminata
I Germanica	IIII Macedonica	XIII Gemina
I Italica	IIII Flavia Felix	XIV Gemina
I Macriana Liberatrix	IIII Scythica	XV Apollinaris
I Minervia	V Alaudae	XV Primigenia
I Parthica	V Macedonica	XVI Gallica
II Adiutrix	VI Ferrata	XVI Flavia Firma
II Augusta	VI Victrix	XVII
II Italica	VII Claudia	XVIII
II Parthica	VII Gemina	XIX
II Traiana Fortis	VIII Augusta	XX Valeria Victrix
III Augusta	VIIII Hispana	XXI Rapax
III Cyrenaica	X Fretensis	XXII Deiotariana
III Gallica	X Gemina	XXII Primigenia
III Italica	XI Claudia	XXX Ulpia Victrix

A Roman legionary (fourth century) (Fectio; ©**)

In the fourth century, we hear of other legions, but at that moment, the legions were no longer the backbone of the Roman army. Their names are included in the following table:

I Iulia Alpina	I Pontica	III Isaura
I Armeniaca	II Iulia Alpina	IIII Italica
I Flavia Constantia	II Armeniaca	IIII Martia
I Flavia Gallicana	II Brittannica	IIII Parthica
I Flavia Martis	II Flavia Constantia	V Iovia
I Flavia Pacis	II Flavia Virtutis	V Parthica
I Illyricorum	II Herculia	VI Gallicana
I Iovia	II Isaura	VI Herculia
I Isaura Sagitaria	III Iulia Alpina	VI Hispana
I Martia	III Diocletiana	VI Parthica
I Maximiana	III Flavia Salutis	XII Victrix
I Noricorum	III Herculia

Chronological catalogue

Before Caesar:

VII, later known as Claudia Pia Fidelis
VIII, later known as Augusta
VIIII, later known as Hispana (disappears 161?)
X Equestris, later known as Gemina

Bust of Julius Caesar. Vatican museums, Rome (Italy). Photo Jona Lendering.

Julius Caesar
(Musei Vaticani, Roma)

Julius Caesar, 58 BCE

XI, later known as Claudia Pia Fidelis
XII, later known as Fulminata

Caesar, 57 BCE:

XIII, later known as Gemina
XIV, later known as Gemina (destroyed 54 by Ambiorix and immediately reconstituted)

Caesar, 53 BCE:

XIV (reconstituted)
XV (destroyed 49-48 in Africa)
XVI (destroyed 49-48 in Africa)

Caesar, 52 BCE:

V Alaudae (disbanded 70)
VI Ferrata

Caesar, 49-48 BCE (using consular numbers):

I, later known as Germanica (disbanded 70)
II
III, later known as Gallica
IIII, later known as Macedonica (reconstituted 70 as Flavia)

Chronological overview of legions

Pansa, 43 BCE:

I
II, later known as Augusta
III, later known as Augusta
IIII
V

Mark Antony:

Bust of Augustus as high priest. Museo Nacional de Arte Romano, Mérida (Spain). Photo Marco Prins.

Bust of Octavian/Augustus as high priest. Museo Nacional de Arte Romano, Mérida.

Octavian, 41-40 BCE:

V Macedonica
VI Victrix
X Fretensis
XV Apollinaris
XVI Gallica (reconstituted 70 as Flavia)
XVII (lost 9 CE)
XVIII (lost 9 CE)
XIX (lost 9 CE)

Octavian 30 BCE:

Battle in Teutoburg Forest:

XVII, XVIII, XIX destroyed

Nero (Glyptothek München; ©**)

Caligula, 39 CE:

XV Primigenia (disbanded 70)
XXII Primigenia

Nero, 66:

I Italica

Nero, 68:

I Adiutrix

Galba, 68:

VII Galbiana: later known as VII Gemina (after merging with I Germanica)
Brief existence of I Macriana Liberatrix

Domitian (Museo Arqueológico, Sevilla)

Vespasian, 70:

II Adiutrix
I Germanica, V Alaudae and XV Primigenia disbanded
IIII Flavia Felix (formerly IIII Macedonica)
XVI Flavia Firma (formerly XVI Gallica)

Domitian, 83:

I Minervia

War against Decebalus, 92:

XXI Rapax destroyed

Trajan, 105:

Uncertain date:

VIIII Hispana (destroyed by the Parthians in 161?)
XXII Deiotariana (destroyed by Bar Kochba?)

Septimius Severus (Archaeological Museum, Thessaloniki)

Marcus Aurelius, 168:

Septimius Severus, 197:

Heliogabalus, 220:

Disbanded: III Gallica

Statue of Philip the Arab. Musei Capitolini, Roma (Italy).

Gordian III, 238?:

Disbanded: III Augusta
Reconstituted: III Gallica
IIII Italica

Philippus Arabs (244-249)?

VI Hispana

Valerian, 253:

Reconstituted: III Augusta

Laelianus (268-269)?

VI Gallicana

Bust of Probus. Musei Capitolini, Roma (Italy). Photo Jona Lendering,

The following units are known from late-ancient sources and are called 'legions'. In fact, they were no longer the elite troops of the Roman empire. The main forces were cavalry units; the legions were the garrisons of the frontier zone.

Aurelian (270-275):

Probus (276-282)

Before Diocletian:

Bust of Diocletian (Arkeoloji Müzesi, İstanbul)

Diocletian (284-305):

Constantius I Chlorus (293-306):

Constans (Louvre, Paris)

Constantius II (337-361)

Constans (337-350):

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