What if Octavian keeps more legions?

[Tibi088]

OTL by the end of the civil wars the number of Legions was well above 50. Octavian decided to drastically lower the number to 28.

What if he decided to keep a significantly larger force? How big an army could he have maintained and how should he have used them? Even if this prowed too constly on the longer run and later emperors decreased the number to OTL levels are there any territories that could and should have been conquered using the available extra forces? Or that werent adequatly protected by what was at hand? The most obvious: Could Teutoburg be avoided or won by 1-2 extra legions?

IMO if he keeps 35-36 legions thats still a drastic decrease however he could stregthen somewhat all the most critical areas - Germania, the Danube and the East. Further a creation of a central army of 4-5 legions - always commanded by either the Emperor or his designated heir (meaning that there would not be an underage and militarily untested heir) to prevent take owers by its commander - would have been a huge benefit to the Empire. This would be stationed in peace time somewhere near or in Italy and would be sent on the area of conflict where together with the local forces they would practically guarantee numerical superiority without actually having to pull away forces and thus weakening other theatres.

 

[Basileus_Komnenos]

The main reason why Augustus reduced the size of the military was that Rome had basically been in a civil war and total political anarchy for the last 100 years. The Roman economy was straining under the weight from the devastation caused by the civil wars, the administrative costs of managing new and large provinces like Gaul, and the payment of these troops. Augustus had to demobilize the large Roman army for financial and political reasons. Keeping all these troops deployed was expensive, and Augustus needed to reduce costs this way. It also served a political purpose because Augustus demonstrated to Rome that the anarchy that had proceeded his reign would now be over since he was now in power. From a military perspective this also made sense since not all regions needed large troop deployments to remain pacified. Some provinces were less prone to rebellion than others and this necessitates a decrease in army size.

Could Teutoburg be avoided or won by 1-2 extra legions?

The problem with Teutoberg wasn't the number of soldiers, but rather the fact that Arminius was a German who fought alongside Rome for years. He knew what Roman strategy and military doctrine was like, and it was ultimately this that allowed him to prevail over Varus's troops. Roman troops of that era were perfect in the open field but floundered when it came to things like forests due to the nature of the Roman Army's rigid formations.

 

[Karolus Rex]

Cassius Dio, provides a good explanation of the Roman views on having too many men under arms "if, on the other hand, we permit all the men of military age to have arms and to practise warfare, they will always be the source of seditions and civil wars. " (Cassius Dio, Roman History, 52.27). For the Romans having too many soldiers it would be seen as a sign of danger, specially in the aftermath of the civil wars of the Late Republic. Augustus had to make his decisions around assuring people that the chaos of the civil wars was finally over, thus the decision to demobilize 32 out of the 60 Legions he had after defeating Antony* which was a great PR move from his part and that he seems to have been very very proud of as we can see from the Deeds of the Divine Augustus:

"I often waged war, civil and foreign, on the earth and sea, in the whole wide world, and as victor I spared all the citizens who sought pardon. As for foreign nations, those which I was able to safely forgive, I preferred to preserve than to destroy. About five hundred thousand Roman citizens were sworn to me. I led something more than three hundred thousand of them into colonies and I returned them to their cities, after their stipend had been earned, and I assigned all of them fields or gave them money for their military service. I captured six hundred ships in addition to those smaller than triremes. "

Now this decision was political, to show that the time of anarchy was over and that the Romans no longer had to fear the existence of large amounts of citizens in arms and because the soldiers themselves wanted to be demobilised so that they could get the lands and gold that Augustus, and in some cases Caesar, had promised them, and the one golden rule of for the leader of Roman soldiers is to never back down on your word to the soldiers. But it was also economical, the Legions were a heavy drain on Augustus coffers, for while he had access to the Aerarium, and could transfer money from the Aerarium to the Fiscus, he was expected to pay the men from the Fiscus and to fiddle with the numbers by transferring money from the Aerarium to the Fiscus this early into his reign would be a political issue.

While the increase to 36 Legions may not look significant, it would be a significant number of men that the Senators, and the rest of the rest of the Roman aristocracy, would take note as 8 Legions is an army of its own and there's not obvious place where to deploy them and bring with them a problem of manpower. OTL Augustus reign was marked by almost constant wars, either to pacify areas (like in Hispania, Pannonia, Gaul, Egypt, etc...) or conquest (like the wars in Germania) and even with "only" 28 Legions, plus the Praetorians and Auxiliary, Roman manpower was stretched to its limits, as we can see by the Roman reaction to the Germanic and Illyrian revolts. More legions means more troops needed which will place more strains on the Roman manpower.

Now on keeping a central army of 4-5 Legions, the political ramifications will be very dangerous. During Augustus time not even the Praetorian Guard was concentrated into one area as a single central army but spread across Italy, with only 3 Cohorts in Rome itself, to place 4-5 Legions in Italy as a central army is a very clear message that Augustus is expecting problems, meaning that he is signalling that he expects more civil conflicts as why else would he concentrate such a large number of men so close by? This makes the propaganda victory that was demobilising the Legions completely void.

Personally I think that keeping more legions will be counterproductive and will cause more political and economical problems both at the short and medium term than any possible benefits. Its worth remembering that the 28 Legions, plus the Praetorians and the Auxiliary, proved to be more than enough to the Roman military needs for the following century until Severus increased the number of legions to 32, in a completely different political and military context.

*note that while he demobilised the Roman soldiers, as far as I am aware there is no sign that the demobilisation of the Auxiliary forces was as extensive as the demobilization of the legionaries;

 

[Tibi088]

For the PR part: Even in my suggestion Rome does demobilze a huge number of troops nearly halving the number of legions. As they dont know the alternative I dont think this would be any less effective for the people of the time in this regard.

The economy is a better argument. However using the extra forces to mop up the existing conflicts swiftly intead of the drawn out continous warfare of OTL might be better. And the army of 25 legions was at times barely adequate to its tasks and Rome even though it was a giant in every sense struggled against foes it should have easily beaten. I know that manpower later became a very severe issue for the army however I think that if evidenced only by the huge number of legions in arms at the time that in the time of Octavian that was the future and not the present.

Teutoburg: I unserstand the role of Armenius but thinking you can beat 3 legions is not the same as thinking you can beat 5 legions. Maybe he doesnt dare to try. And even if he does having nearly twice the number of man on your side in a fight tends to increase your chances of victory.

A central army is dangeropus politically i agree. Its vital that the emperor has it unde control - thats why I proposed it being always commanded by either the emperor or his heir aparent. Seeing the praetorians issue with loyalty I dont think it would become much worse.

 

[Karolus Rex]

For the PR part: Even in my suggestion Rome does demobilze a huge number of troops nearly halving the number of legions. As they dont know the alternative I dont think this would be any less effective for the people of the time in this regard.

The economy is a better argument. However using the extra forces to mop up the existing conflicts swiftly intead of the drawn out continous warfare of OTL might be better. And the army of 25 legions was at times barely adequate to its tasks and Rome even though it was a giant in every sense struggled against foes it should have easily beaten. I know that manpower later became a very severe issue for the army however I think that if evidenced only by the huge number of legions in arms at the time that in the time of Octavian that was the future and not the present.

Teutoburg: I unserstand the role of Armenius but thinking you can beat 3 legions is not the same as thinking you can beat 5 legions. Maybe he doesnt dare to try. And even if he does having nearly twice the number of man on your side in a fight tends to increase your chances of victory.

A central army is dangeropus politically i agree. Its vital that the emperor has it unde control - thats why I proposed it being always commanded by either the emperor or his heir aparent. Seeing the praetorians issue with loyalty I dont think it would become much worse.

While it many not look much, 8 extra Legions is a significant amounts of men that won't be overlooked as they are an army, by any Roman metrics 8 legions are an army on their own and he will have to justify the need to keep them, as Cassius Dio explained the Romans understood the need to keep a standing army, they just couldn't rely on the old systems any more, they were very well aware of the dangers of having too many men under arms and an extra eight legions would fall under "too many".

I would argue that with 8 extra legions you will be draining on the resources to handle said affairs, take the Great Illyrian Revolt, between ten and fifteen legions were involved in this 3 years long campaign in which the Legions were suffering from manpower issues, there just weren't enough volunteers to keep the legions at full strength and employing the conscription mechanism to gather levies of Roman Citizens is something that he just can't use for political reasons, he could, and indeed he used, said mechanisms to gather levies of non-citizens but that doesn't fixes the issue of lack of volunteers to the legions.

The Praetorians were always loyal to Augustus, there is no indication that their loyalty to him was ever in doubt, the infamous Praetorian loyalty problems would only show themselves later, starting with Tiberius. But even ignoring the Praetorians he had no need to place an actual army in Italy, which would be political suicide, when the VII and XI Legions were garrisoned in Illyria, officially a frontier province but that was close enough to Italy to handle any problems that could come up. Now the idea of a central army is good, it would be developed by several Emperors later on when the political climate made such a creation a necessity, but during Augustus reign such a force would cause too many political problems and show the wrong signals.

 

[Fabius Maximus]

Personally I think that keeping more legions will be counterproductive and will cause more political and economical problems both at the short and medium term than any possible benefits. Its worth remembering that the 28 Legions, plus the Praetorians and the Auxiliary, proved to be more than enough to the Roman military needs for the following century until Severus increased the number of legions to 32, in a completely different political and military context.

I'd dispute the idea that Rome's OTL army was "more than enough". Enough, certainly, as the Empire survived and prospered for some two centuries after Augustus' death, but the difficulty Rome had in, say, putting down the Illyrian rebellion or recovering from Teutoburg, or later in dealing with the Marcomanni, indicates that there wasn't much "give" in Rome's army. They could handle their regular duties just fine, but found it difficult to deal with an unexpected crisis; and when you had multiple simultaneous crises in the third century, the system collapsed and had to be effectively reconstituted under a new plan by Diocletian.

 

[Karolus Rex]

I'd dispute the idea that Rome's OTL army was "more than enough". Enough, certainly, as the Empire survived and prospered for some two centuries after Augustus' death, but the difficulty Rome had in, say, putting down the Illyrian rebellion or recovering from Teutoburg, or later in dealing with the Marcomanni, indicates that there wasn't much "give" in Rome's army. They could handle their regular duties just fine, but found it difficult to deal with an unexpected crisis; and when you had multiple simultaneous crises in the third century, the system collapsed and had to be effectively reconstituted under a new plan by Diocletian.

Given the overall performance I put it as adequate as under normal circumstances it managed to handle military affairs that Augustus predicted would affect the Empire, and taking into account the political environment that affected the establishment of the permanent army.

When the Augustinian Military System was established, it was done so with the idea that this would be a time of less military crisis, the symbolic closing of the gates of Janus’ temple being an example of what Augustus was most likely expecting, which is ironic as the Empire would spend the following century in almost constant conflict and that would slowly erode the foundations of said military system. Was it an oversight? Yes, and the consequences of said oversight are enough for us to have a full debate, but all things into consideration I dare say the Roman military handled affairs as well as they could.

 

[Fabius Maximus]

Given the overall performance I put it as adequate as under normal circumstances it managed to handle military affairs that Augustus predicted would affect the Empire, and taking into account the political environment that affected the establishment of the permanent army.

When the Augustinian Military System was established, it was done so with the idea that this would be a time of less military crisis, the symbolic closing of the gates of Janus’ temple being an example of what Augustus was most likely expecting, which is ironic as the Empire would spend the following century in almost constant conflict and that would slowly erode the foundations of said military system. Was it an oversight? Yes, and the consequences of said oversight are enough for us to have a full debate, but all things into consideration I dare say the Roman military handled affairs as well as they could.

I don't want to sound too harsh on Augustus: his constitutional settlement survived fundamentally unchanged for over two centuries, which puts him ahead of most other would-be statesmen, and the military forces he kept were clearly sufficient to secure the Empire's territorial integrity during Augustus' own time. But systems of professional, long-service armies like the one he adopted have certain limitations; in particular, since it's difficult to replace soldiers or to raise new ones quickly, it's hard to recover from disasters (like Teutoberg) or deal with sudden crises (like the Illyrian revolt or the Marcomannic war). That's not to say that Augustus made the wrong choice in adopting the system he did (the old Republican model of raising armies for a specific war and then disbanding them afterwards was clearly unsuitable for garrisoning a large empire), just that the Imperial system was in some respects more fragile than the one of the Middle Republic (there's no way Imperial Rome would be able to keep raising army after army like in the Punic Wars, for example). So I think you could make a case that it would be better for him to have kept a few more legions around, simply to leave the army with more slack: if you have more troops than necessary along each of the frontiers, you can draw some away to deal with rebellions or reinforce other sectors without compromising the security of the rest of the Empire.