When did the Roman Army decline?

[Flavivs Aetivs]

Chalons? Yes that estimate would be accurate, Aetius fielded about 22,500 men at the Battle of the Catalaunian Plains, most of them Veteran Pseudocomitatenses with a core force of about 5000-10000 Bucellarii and Auxilia Palatina (Elite Crack Troops). All of them had been equipped with Armor and were well supplied, as evidenced by Sidonius Apollinaris' letters to Tonatius Ferreolus. In those letters he also mentions that there were enough supplies leftover to equip (some of) and feed the 40,000-ish Barbarian Allies Aetius had recruited, who by this point were of the same quality as the regular Roman soldiers. It took them about 2 years to prepare for this invasion, and there was also a famine in Italy at the time.

However, your view of the army is highly misguided.

Comitatus may enlighten you:
http://www.comitatus.net/armytroops.html

[Mrbsct]

How am I misguided? To say the Army right at the time of Adrianople was the same quality and quantity as the Principate, 3rd century Crisis or even the army of Constantine is misguided.

[AMELIANVS]

Andy, It is nice how you intentionally chose such pictures to make look Principate soldiers better equipped than those of Dominate times.
But:
1)Plate armour is nothing like a Sign of the peak of the Roman army

2)Mail was always the most commonly used form of protection not at all inferior to plate armour.

3)From various reasons you would always find some Roman soldiers fighting without any armour at all even during Principate

4)Properly combat armed late roman soldier was definitely NOT any significantly lower in quality of his equipment then his principate predecessor.

[Justin I]

Vegetius doesn't seem to be an unreliable source, he actually knows how military training and organization works and he is still studied in modern military academies.

He's a great source for anecdotes and advice about military training and recruitment, but he wasn't a historian. De Re Militari is sort of like the Strategemata by Sextus Julius Frontinus; it's certainly worth reading, but as has been said here earlier, take it with a grain of salt.
I tend to agree with Evan that the Roman military didn't really start declining until the early 5th century. From the time of Diocletian until Adrianople, the Roman military's record in battle against foreign "barbarians" was actually quite good. The campaigns of Julian and Valentinian, especially, showed that Rome was still the preeminent power, at least when it had its political house in order.

As far as the relative paucity of troops who showed up at the Battle of Adrianople, remember that Valens had recently deployed large units to the east because of rumors that the Armenian king was planning to revolt and side with Persia. And remember that Gratian was on his way with another army but didn't get there soon enough. The Goths really caught Valens flat-footed and unprepared.

[ValentinianVictrix]

I fully admit that unlike the Crisis of the Third Century, where combined armies of Goths and other Germanic's plundered and ravaged throughout Greece, the southern coastline Black Sea provinces, the provinces bordering the Rhine and Danube, even down as far as Rome itself in Italy, and the Parthians followed by the Sasanids were overrunning large areas of the Eastern provinces, the situation after Adrianople appeared less serious. Why the Romans were unable to eject the Goths from within their borders during the 4th & 5th Century AD, like they had during the previous century, has not been fully explained to my satisfaction. One plausible reason was that the Goths were still needed for future campaigns against the Sasanids and then possibly to aid against the Huns. Of course the Goths could not return to their former homelands as the Huns had now taken possession of them, which was a far different sitution than the previous century.

[Flavivs Aetivs]

Well, the huns hadn't taken "possession" of them. In reality what the Gretungi had been fighting were minor raiding parties on the other side of the Dnieper. The Gretungi forced the Tervingi to move as members of their group fled into Carpathia, and eventually both groups had significant numbers show up as refugees on the Roman borders.

But it was ethnogenesis, they were under pressure but it wasn't the whole "migration theory" concept with them forcing other tribes out of their lands through swathes of conquest. About 6 distinct Gothic groups remained in the Carpathian and Bosporan regions until the 480's and they went on to form the Amailic Goths and then the Ostrogoths. Some remained until the 6th or 7th centuries.

As for forcing the Goths back over the border? In theory they didn't have to let them cross in the first place, they could have blockaded the river with Lusoriae and Limitanei.

I think they let the Goths cross and stay because Valens needed them as recruits for his upcoming Sassanid campaign, and expected them to Romanize and dissappear as an individual group of "Goths" over the next few decades.

Furthermore we don't see evidence of the Huns in the region of Dacia and Pannonia until Aetius is sent there under Uldin in 408 (and stays until Octar dies in the year 417 or 418, same time his father Gaudentius dies).

[ValentinianVictrix]

'Well, the huns hadn't taken "possession" of them. In reality what the Gretungi had been fighting were minor raiding parties on the other side of the Dnieper. The Gretungi forced the Tervingi to move as members of their group fled into Carpathia, and eventually both groups had significant numbers show up as refugees on the Roman borders.'

It was not a few 'raiding parties' that put pressure on the Goths, the Goths had been fighting against Alan raiders for years and they had not forced the Goths to move westwards like the Huns subsequentely did. The Greuthingi goths had been battling the Huns probably for several decades before the Greuthingi were finally routed and forced to move westwards. Athanaricus was noted by Ammianus as originally being a Greuthingi chief, and he subsequently became King of the Tervingi goths until the civil war between himself and Fritigern led to a split, with some Tervingi going into the Carpatians with Athanaricus, the majority following Fritigern southwards towards the Danube. A Tervingi force led by Athanaricus joined up with a Greuthingi force and they planned a joint attack on the Huns. Unfortunately, the Huns avoided the gothic scouting party and attacked the combined gothic encampmentat night, slaying many and Athanaricus was forced to flee to the Carpatians again where he then moved out and attempted to repair the old Roman frontier wall in Dacia as a defence but he was attacked by the Huns before he could do so and he was forced to flee again.

'But it was ethnogenesis, they were under pressure but it wasn't the whole "migration theory" concept with them forcing other tribes out of their lands through swathes of conquest. About 6 distinct Gothic groups remained in the Carpathian and Bosporan regions until the 480's and they went on to form the Amailic Goths and then the Ostrogoths. Some remained until the 6th or 7th centuries.'

Most of the Gothic tribes who remained behind in their former homelands were technically vassals to the Huns and they only totally broke free from Hunnic control after defeating the Huns at the Battle of Nedao in 454AD.

'As for forcing the Goths back over the border? In theory they didn't have to let them cross in the first place, they could have blockaded the river with Lusoriae and Limitanei.'

Valens allowed them to cross as he had an agreement with them to rehome them within the Empire in exchange for military service against the Sasanids. Unfortunately the Roman officers supervising the Danube crossings so badly mistreated the Goths that the Goths rebelled, killing the officials and the forces sent to quell the rebellion, which allowed the Goths to reequip themselves with Roman arms and armour. A large number of Goths had been allowed to cross the Danube with their arms and historical commentators at the time felt that was a deadly mistake. Due to the sheer size of the multitude of Goths lining the banks of the Danube it is doubtful if the Roman riverine forces would have been able to contain them or prevent crossings, they certainly were powerless to prevent a later crossing by the Greuthingi.

'I think they let the Goths cross and stay because Valens needed them as recruits for his upcoming Sassanid campaign, and expected them to Romanize and dissappear as an individual group of "Goths" over the next few decades.'

Absolutely agree with you on this point.

'Furthermore we don't see evidence of the Huns in the region of Dacia and Pannonia until Aetius is sent there under Uldin in 408 (and stays until Octar dies in the year 417 or 418, same time his father Gaudentius dies). '

There were certainly Huns in that region before 400AD as they are reported as crossing the Danube to make small scale raids into Roman territory. Some were recruited and sent to Africa on that date as well if memory serves. There must have been significant numbers of Huns in that region prior to 408 or Aetius would not have been sent there just because of the presence of a few raiding parties.

[Mrbsct]

I just don't get how the Late army of post-Julian is somehow the "same quality" when you say "lack of manpower" or "recorvering". 30 million people and they can barely even recover the manpower, relying on Foederetii. That is nothing compared to even the 3rd century Crisis where entire armies were lost. The decline is due to politics, economics, military defeats, and civil wars. My question is what event(like what Civil War?) that caused it?

As far as Adrianople, the Elite Schoe Cavarly literaly broke ranks without any orders and encircled the Gothic encampment only to get driven off easily by the Gothic calvalry.

[AMELIANVS]

If you are only searching for one single event you can't be successful in your search Andy.

[Flavivs Aetivs]

The Decline of availible Manpower was due to several factors, and that decline didn't occur until the Invasion of 406 when Roman control of Gaul and Spain broke down, which was probably one of the biggest recruiting grounds as they still retained a militarized culture. People started looking to a career in the church rather than the Bureaucracy or the Military as well, and they preferred their local Bishop as a source of Leadership rather than their Dux Limitis.

Furthermore a decline in manpower does not mean a decline in Quality. Aetius' Army was predominately Limitanei drawn into the Field Army called pseudocomitatenses, and Aetius had the leadership quality to demand complete loyalty and a high level of discipline from his troops, which resulted in a successful army full of Veteran troops. Aetius never suffered a military reverse (except to Boniface in a Civil War) and a victorious army is one where recruits will flock to the standards

[ValentinianVictrix]

I just don't get how the Late army of post-Julian is somehow the "same quality" when you say "lack of manpower" or "recorvering". 30 million people and they can barely even recover the manpower, relying on Foederetii. That is nothing compared to even the 3rd century Crisis where entire armies were lost. The decline is due to politics, economics, military defeats, and civil wars. My question is what event(like what Civil War?) that caused it?

As far as Adrianople, the Elite Schoe Cavarly literaly broke ranks without any orders and encircled the Gothic encampment only to get driven off easily by the Gothic calvalry.

In December 1944 the population of the UK was just over 40 Million, the population of the USA was approximately 135 million. Yet, despite this both nations field armies were almost at breaking point when the Battle of the Bulge broke out on 16th December of that year. Its been estimated that the UK only had two regiments worth of reserves, the USA about 12, if the Germans had reached their objective of Antwerp then the Western Allies would have had to negotiate a peace.

So, its not your population levels that count, but the numbers you can train in time to be combat effective. And recruits literally do not grow on tree's, you have to replace men through recruiting the able, then the old and young and then finally you have to rely on increased birth rates to provide the next generation of soldiers. It can take decades to build a nations army up to full strength.

[Michael Kerr]

Would the fact that by Aetius's time he could not call for troops or military support from Eastern empire unlike Principate emperors who could transfer armies or units from east or west to converge on troublespots. May be Eastern Empire gave west covert support but it looked to me that they just sat out the conflict between Aetius & Attila as by this time they were 2 separate empires. With revenues cut by loss of Africa & Spain & no access to Eastern troops or reinforcements the western empire would have perpetual manpower problems.
Regards
Michael Kerr

[Mrbsct]

So Gratian and Theodosis decided not crush the Goths after Adrianople purely due to political reasons not military and manpower issues? The manpower issues started after Constantine's tax law and religious reforms if anything.

I don't understand how the Limitanei are somehow "good". Julian seemed not to even rely on them in Gaul. There is a reason why by the time of Strasbourg, commanders were very conservative not to sacrifice their precious Comiatenses.

[Michael Kerr]

While speaking of Limitanae & Comiatenses while reading a book on Yuan China in early 14th century, they like the Romans had ‘regular chiliarchies' like Comiatenses who formed the main fighting force & ‘farming chiliarchies' consisting of about 2000 men who were the outpost troops who because of the devastation of the Mongols basically became full time farmers just to survive on frontier with little time for training & weapons maintenance so quality was reduced & they were meant to hold back invaders till regulars were ready to engage enemy. Although different times it's funny how they both turn to similar approaches in maintenance of a large frontier. Not comparing Roman Limitanae as they probably had a busy time fighting off barbarians with no time for full-time farming like their eastern counterparts who quickly lost their martial skills.
Regards
Michael Kerr

[Flavivs Aetivs]

Would the fact that by Aetius's time he could not call for troops or military support from Eastern empire unlike Principate emperors who could transfer armies or units from east or west to converge on troublespots. May be Eastern Empire gave west covert support but it looked to me that they just sat out the conflict between Aetius & Attila as by this time they were 2 separate empires. With revenues cut by loss of Africa & Spain & no access to Eastern troops or reinforcements the western empire would have perpetual manpower problems.
Regards
Michael Kerr

That's more or less what happened. The East had always acted as a financial prop for the West, and the split only actually had two effects on the West: The East and West had seperate militaries and Revenues.

After 414, Gaul and Spain were no longer viable tax bases. By 435, Mauretania, Raetia, Noricum, and Pannonia were no longer Viable Tax Bases. By 439, Numidia and Africa were no longer Viable Tax bases.

This culminated in a cut of around 40,000 troops for the loss of Africa alone, and by 450 the Army probably only numbered around 40,000 men in field armies across the empire, with Barbarian foederati taking the place of the "Limitanei" for the most part (although Limitanei seemed to still be intact throughout much of Gaul serving as town garrisons)