Varied Size of the Roman Legions

Roman Legion Size

The word “legion” is often understood to refer to a massive number of soldiers, specifically soldiers of the Roman army in the days when the Roman Empire still existed. They exist to protect land during the war and also protect their king.

Even up to death, they committed to protect their king and lands. It means leaving their wives and children behind for the glory to serve the crown. This legion has stayed for many years and evolved.


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As a descriptive term, “Legion” connotes a huge number, but what the number is exactly has been subject to debate and discussion even among historians. To simplify the matter, however, it is also generally understood that a Roman legion size numbered up to 5,000 soldiers.

Members of the Roman army were called legionnaires, and at the pinnacle of the Roman Empire’s power, a single legion had 4,200 to 5,000 legionnaires. Each also had 3,000 equities. Equities are a section of Roman society that had wealth and political influence. Citizens from these privileged classes formed the original cavalry of the Roman army.

The Roman Legion Size Throughout History

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Many smaller formations comprised a typical Roman legion, with the numbers changing depending on the period in history wherein they were established. For instance, during the height of the Roman Republic, it was possible to separate a legion into three lines, with each line having 10 maniples.

In the latter years, during the imperial period, it was stated that a Roman legion size comprised 10 cohorts, with each having five or six centuries (a century refers to 100 soldiers). Eventually, the composition of legions or the Roman legion size became smaller, reduced to 1,000 to 1,500, but more legions were created.

From Equites to the Triarii

Each legion was composed of Equites (the cavalry), Velites (light infantry); and the Heavy infantry. In turn, the Heavy infantry was composed of the hastati who were soldiers with no previous experience in warfare and combat; the principles, or the soldiers who had more military campaign experience; and the triarii, the veteran soldiers.

The triarii were the soldiers who were battle-tested and experts at warfare, and in formations they formed the last line of defense right after the principes and the hastati.

From 50 Legions to 25

Throughout Roman history, the names and numbers of Roman legions size grew and dwindled and then grew again as legions were formed then disbanded, then reformed. As of the last record of historians, the highest number of 50 legions were identified, and these existed until the time the Roman Empire fell when the figure fell to 25 to 35 legions.


Over the years the Roman legion size varies. The Roman empire has many soldiers and in time this has decreased or increased. They like to break down their legions in groups to distribute more force and power. It is the influence of the Greek era that made them this strategy.

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