"Caesarean Roman Legion Organization / Troop Types Numbers?" Topic

This is fairly common knowledge:

As Roman armies of the late Republic and Empire became larger and more professional, the cohort, with an average field strength of 360 men, replaced the maniple as the chief tactical unit within legions. In the military operations of Lucius Cornelius Sulla and Julius Caesar, a legion was composed of 10 cohorts, with 4 cohorts in the first line and 3 each in the second and third lines. The 3,600 heavy infantry were supported by enough cavalry and light infantry to bring the legion's strength up to 6,000 men.

But what was the make up of the 2400 other troops?

Are there any good reference works?

Orders of battle? Formations for battle?

What makes you think that 1st century Republican legions got topped up to 6000? At the Battle of Pharsalus Caesar had 22,000 legionaries in 8 legions plus 1000 cavalry and some light troops. Nothing close to 48,000 men.

It's not what I think. It's what I read:

link

link

For example, John Lydus, writing in the mid-sixth century, described a legion of 388 BC as 6000 infantry strong. 13 Suetonius refers to the strength of the legion as 5600, and
although writing during the early Empire, he was most likely referring to a republican organisation. Sextus Pompeius Festus, writing in the late second century AD, mentions a
legion 6200 strong, and Servius, writing nearly 200 years later, describes a legion comprised of 6000 infantry and 300 cavalry. Both of these also seem to be republican organisations 14.

The lack of agreement between numbers need not necessarily be a concern, however, because Polybius' expanded 5000-man legion does not differentiate between infantry and cavalry. It is uncertain whether Polybius meant to include the cavalry in this 5000 or whether it was an adjunct as it was with his lower figure of 4200. If the cavalry contingent was meant by Polybius to be in addition to the 5000, a total of 5300 would be alTived at. This fits easily into both of Livy's descriptions. In the first instance the numbers agree exactly with Livy's 5000 infantry and 300 cavalry and in the second they fit easily into the 5200-6000 range. The search for a standardised legion complementmay be in vain, however. Each year the size of the legions was decreed by the Senate, and although this would create a customary or traditional allocation of resources, nowhere do we have evidence of any legalised standard for legionary strength during this period. 15 Thus the sources may disagree because there was no standard until the time of Augustus, and legion strengths varied according to circumstances. 16 It is important to
note, however, that the numbers making up a legion's complement may have varied, but the basic organisation remained the same. Rather than change the basic structure of the legion, the sub-units that made up the whole were increased or decreased in strength of numbers.

Could they be wrong? Sure.

With so many legions during Caesar's time, there must be some records (?).

In the following table, one can see the development of the army of Julius Caesar: when he became governor of Gallia Cisalpina and Gallia Narbonensis, he took charge of four already existing legions (numbered VII, VIII, IX and X), but during the campaigns in Gaul and in the Civil war against Pompey, the army grew. When Caesar was murdered, there were many more legions, which were taken over by Caesar's successors.

Light red indicates a normal serving unit; dark red a veteran legion; grey means that it sides with Caesar's murderers; green and yellow indicate serving with Mark Antony or Octavian repectively.

link

Which is why I would like to find some good books about the organization of the legions and other military formations (ie Marines, etc).

I guess what I really want to know is the ratio for archers, slingers, bolt throwers, cavalry (types thereof), etc.

Non legionary troops.

The 3,600 heavy infantry were supported by enough cavalry and light infantry to bring the legion's strength up to 6,000 men.

I think they are factoring the auxiliary infantry cohorts and auxiliary cavalry into that 6000, which makes me very doubtful about the quality of the information provided. Most auxiliaries were not light infantry.

@wymers The Roman Army: The Greatest War Machine of the Ancient World from Osprey. Covers all Roman eras in detail. According to the booK during Caesar's time there were supposed to be 80 men per century. 6 centuries per cohort with 10 cohorts. However the 1st Cohort is every legion was a double cohort with 12 centuries. Theoretical strength of 5280 legionnaires. It actually typically came to about 4000 active soldiers with fewer fit for duty.

Velites and Roman cavalry disappear from the records and are replaced with auxiliaries. Auxiliary units didn't go beyond a cohort in size. There is no ratio consistent from army to army on campaign. Only that legionnaires are the core of every army.

With the Marian reforms, as smithsco suggest, all the other legion troops were disbanded and the Legion became filled with Roman heavy infantry (legionnaires.) Auxiliary units were attached to various legions but they did not become part of the legion and could be moved around at will. I don't think there is a simple set of ratios that you can use.

There is an interesting article on Roman Legion Lanciarii (light infantry) here link

Still my favorite site for information on Roman legionary organization:
link

Wmyers,

Your second post is about legions prior to the time of Caesar which had an entirely different organization. The armies of Caesar's time are organized according to the reforms of Marius. Polybius describes the armies of the middle republic

The legion of 388 B. C. is from the early republic and has a different organization than the one described by Polybius. The legion of 388 B.C was composed of multiple lines of maniples and included Princepes, Hastatii, Rorarii, Accensi, and Triarii.

The army Polybius described consisted of Hastatii, Princepes, Triarii and Velites and numbered about 4200 infantry, but in times of emergency could have an additional 600 men added to the Hastatii, Princepes, and Velites increasing it to 6000 infantry.

Caesar's legions averaged 3000 to 4000 men depending on how long they had been campaigning and time since they were raised. Archers were almost non existent in Caesar's armies. Light infantry and cavalry were provided by Gallic allies.

As mentioned at Pharsalus Caesar had eight legions with 22000 infantry. Pompey had eleven legions with 36000 men. Two of Caesar's legions are noted as being about half strength.

Caesar's Gallic Wars provides some information on how many legions and additional supporting troops were at each battle. "Armies of the Macedonian and Punic Wars", "Armies and Enemies of Imperial Rome" and "Lost Battles" provide summaries of the forces at each battle. There are other books that also cover the Roman armies of various periods. "Lost Battles" includes extensive notes referencing ancient sources for the battles included in the book.

Classic organisation was first cohort had five double centuries giving 800. Other nine had six centuries so 480 a pop giving 4320. So total of 5120 grunts.

Each century had a command unit of around four (centurion, optio, cornicern, signifer) so 59 centuries gives another 236 plus the guy with the eagle giving an infantry fighting force on paper around 5357.

Added to that were 120 equites who were presumably actual Romans and the artillery crews who I assume are dedicated crews and not taken from the centuries.

Your second post is about legions prior to the time of Caesar which had an entirely different organization. The armies of Caesar's time are organized according to the reforms of Marius. Polybius describes the armies of the middle republic

This is what I had read previously, as well. However, the paper by Hoyt ( link ) I linked above appears to state how weak such claims actually are and how little evidence there apparently is for them.

during Caesar's time there were supposed to be 80 men per century. 6 centuries per cohort with 10 cohorts.

Classic organisation was first cohort had five double centuries giving 800. Other nine had six centuries so 480 a pop giving 4320. So total of 5120 grunts.

This is more in line with Hoyt's paper.