Roman Legion composition?

[Atilius]

A centurion must have had to detach his men into smaller groups

This does not imply the existence of an eight man unit of organization.

We also know that legionaries formed in lines four men deep.

Do we? Cite a reference for that.

But there are a few things we know about Roman Army besides what Polybus tells us. For example, we know a Legion commander or Legate had 6 Military Tribunes. What was their command?

In fact, almost the first thing Polybius tells us about the Roman army in his discussion of the Roman army (6.19) is that six military tribunes were posted to each legion. Later (6.34), he states that rotating pairs of tribunes shared command of the legion:

They [the Tribunes] divide themselves in twos, and each pair is on duty for two months out of six; they draw lots for their turns, and the pair on whom the lot falls takes the superintendence of all active operations. The prefects of the socii divide their duty in the same way. At daybreak the officers of the cavalry and the centurions muster at the tents of the Tribunes, while the Tribunes go to that of the Consul. He gives the necessary orders to the Tribunes, they to the cavalry officers and centurions, and these last pass them on to the rank and file as occasion may demand.

During this period, when it was extremely rare for a Consul to command more than two legions, the Consul had no need of a legate: he commanded his legions through the two tribunes currently in charge of each. It's also difficult to see how, if a Polybian legion were divided into ten cohorts, the command of the cohorts would have been distributed among the remaining four tribunes.

[Lanceari]

During this period, when it was extremely rare for a Consul to command more than two legions, the Consul had no need of a legate: he commanded his legions through the two tribunes currently in charge of each. It's also difficult to see how, if a Polybian legion were divided into ten cohorts, the command of the cohorts would have been distributed among the remaining four tribunes.

Your refer to the period when it was "extremely rare for a Consul to command more than two legions."

You correctly state that for a long period of time Rome only had two legion. However, during this period, each legion was commanded by a separate consul. (There were two consuls.) And, during this period, it was most exceptional for both legions to work together.

The whole idea between the two consuls and two legion arrangement was based on the notion that no single person should ever command the entire army, so as to avoid a coup. As a result, there was no provision for both legions to work together under a single command. Christian Meier wrote a great book where he takes some time to explain the Roman Constitution and gives great insights into it. I strongly recommend it.

Combining both legions, as in Cannae, was truly exceptional. Roman ways did not provide a command solution for such an exceptional circumstance. In fact the whole idea between the two legion and two consul arrangement was to prevent a single command. At Cannae the two consuls marched together alternated command of the entire army, one day each. A rather counterproductive solution, and clearly an exceptional arrangement under exceptional circumstances.

Furthermore, you state that "Polybius tells us... that six military tribunes were posted to each legion." Accordingly if you ever were to combine the two legions together, you would get 12 military tribunes for two legions. 6 +6 = 12.

In the very exceptional case where both consuls marched together in a combined army, at least one of the consuls would keep direct command of his legion while the other consul assumed command of the combined force. So only one legion, at most, was left without his consul commander. And, hence only in one legion needed to make special arrangements you cite. The other legion would retain its own consul plus its full staff of Military Tribunes.

The combined army would have 2 consuls and 12 Military Tribunes. One consul to exercise control of the entire army. One consul to command one Legion. 10 MT's would be available to assign 1 Military Tribune for each pair of cohorts. And you still have two Military Tribunes left. As per your suggestion, these two MTs could take operational command of the remaining Legion. Alternatively, one of them could take command of this remaining Legion, while the other MT took command of the cavalry.

Finally, we agree, if the consul (or legate) was missing, Romans most have provided a command solution where the military tribunes assumed temporary command in his absence. But this was a temporary solution in the absence of the consul (or legate). If the consul (or legate) was present, he was the commander of the legion.

[bigmilt16]

Your refer to the period when it was "extremely rare for a Consul to command more than two legions."

You correctly state that for a long period of time Rome only had two legion. However, during this period, each legion was commanded by a separate consul. (There were two consuls.) And, during this period, it was most exceptional for both legions to work together.

The whole idea between the two consuls and two legion arrangement was based on the notion that no single person should ever command the entire army, so as to avoid a coup. As a result, there was no provision for both legions to work together under a single command. Christian Meier wrote a great book where he takes some time to explain the Roman Constitution and gives great insights into it. I strongly recommend it.

Combining both legions, as in Cannae, was truly exceptional. Roman ways did not provide a command solution for such an exceptional circumstance. In fact the whole idea between the two legion and two consul arrangement was to prevent a single command. At Cannae the two consuls marched together alternated command of the entire army, one day each. A rather counterproductive solution, and clearly an exceptional arrangement under exceptional circumstances.

Furthermore, you state that "Polybius tells us... that six military tribunes were posted to each legion." Accordingly if you ever were to combine the two legions together, you would get 12 military tribunes for two legions. 6 +6 = 12.

In the very exceptional case where both consuls marched together in a combined army, at least one of the consuls would keep direct command of his legion while the other consul assumed command of the combined force. So only one legion, at most, was left without his consul commander. And, hence only in one legion needed to make special arrangements you cite. The other legion would retain its own consul plus its full staff of Military Tribunes.

The combined army would have 2 consuls and 12 Military Tribunes. One consul to exercise control of the entire army. One consul to command one Legion. 10 MT's would be available to assign 1 Military Tribune for each pair of cohorts. And you still have two Military Tribunes left. As per your suggestion, these two MTs could take operational command of the remaining Legion. Alternatively, one of them could take command of this remaining Legion, while the other MT took command of the cavalry.

Finally, we agree, if the consul (or legate) was missing, Romans most have provided a command solution where the military tribunes assumed temporary command in his absence. But this was a temporary solution in the absence of the consul (or legate). If the consul (or legate) was present, he was the commander of the legion.

That is very interesting insight into the command structure of the legions. How would one simulate this in the game? It would be virtually impossible to conquer some areas of the map or defend Roman holding with merely two "legions" composed of two half stacks.

Besides, in Rome, were there not numerous legions throughout the republic/empire? Is one solution to place tribunes in charge of the "stacks" and have them answer to praetors/consuls in game?

I guess my question is more about how to simulate such a unique command structure through houserules considering that the game was never designed to appreciate this.