Roman Legionary tattoo Picture

A Roman legion (from Latin legio "military levy, conscription", from legere "to choose") 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 up to 5,400 soldiers, originally divided into 10 maniples and later into cohorts each with 480 soldiers. Maniples or cohorts were divided into six centuries of 80 men each. In reference to the early Roman Kingdom (as opposed to the Roman Republic or empire), "the legion" means the entire Roman army.

For most of the Roman Imperial period, the legions were a part of the Imperial army and formed its elite heavy infantry, recruited exclusively from Roman citizens (provincials who aspired to citizenship gained it when honorably discharged from the auxilia). Each legion always included a small cavalry attachment. The Roman army (for most of the Imperial period) consisted mostly of "auxiliary" cohorts,[1] who provided additional infantry, and the vast majority of the Roman army's cavalry.

Because of the enormous military successes of the Roman Republic and the Roman Empire, the legion has long been regarded as the prime ancient model for military efficiency and ability.

from en.wikipedia.org/wiki/Roman_le…

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.

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.

Early Empire legions

The Roman empire and legions deployed in 125 AD, in the time of emperorHadrian.
from en.wikipedia.org/wiki/List_of_…
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