The Byzantine themes and their manpower according to 10th century historian Ibn al-Faqih

[Manuel I Komnenos]

Four centuries is plenty of time for a recover, just look at post bubonic plague Europe.

I think it's clear the east suffered decline, not as much the west, but it was quite severe.

As neoptolemos noted, the plague had a devastating effect, but the answer to the question 'why the empire's population never recovered' is because medieval society was much different compared to that of antique. Urbanization in the east declined and the huge cities of the Roman era were gone, besides Constantinople, Antioch and a few others. The primary social and economic unit of the empire was the "chorion", the village, a settlement of a few hundred families with farms. The transition in the Roman society is evident from the gradual disappearance of the senatorial aristocracy and the emergence of a landed one. Plus, of course, you had the Arabic and Slavic raids, which devastated much of the countryside, famines, harsh winters etc.

[hellheaven1987]

The transition in the Roman society is evident from the gradual disappearance of the senatorial aristocracy and the emergence of a landed one.

To be fair, such transition already started since 1st Century BC; it is arguable that part of reasons why Crassus was included in First Triumvirate was he represented the rising merchant/landlord class.

[Caesar Germanico]

As neoptolemos noted, the plague had a devastating effect, but the answer to the question 'why the empire's population never recovered' is because medieval society was much different compared to that of antique. Urbanization in the east declined and the huge cities of the Roman era were gone, besides Constantinople, Antioch and a few others. The primary social and economic unit of the empire was the "chorion", the village, a settlement of a few hundred families with farms. The transition in the Roman society is evident from the gradual disappearance of the senatorial aristocracy and the emergence of a landed one. Plus, of course, you had the Arabic and Slavic raids, which devastated much of the countryside, famines, harsh winters etc.

In short: a softer dark age.

[white-wolf]

12 millions is too much. Even the start of 20th Century there was less at Anatolia.

[Basileos Leandros I]

12 million is not that much of a surprising number, given the extensive farming and overall good health of the Byzantine economy that would have supported a population expansion.

[Kitsunegari]

Also the monasteries, despite producing art and literature, were an alarming drain on manpower at times. It's hard to imagine taking the vow as a monk as an attractive option today, but back then it certainly was.

[Magister Militum Flavius Aetius]

That applies as far back as the 4th century, when the locals in the West saw the role of a church life as preferable to that of the Cursus Honorem or a military career. The majority of the manpower problem in Late Antiquity was caused by the possessores or landowning class though, who refused to give troops to the Army. Eventually what you had was an endless spiral where Flavius Aetius was forced to supply his army with barbarians to keep the manpower in Roman units up, meaning he had to settle more foederati, which couldn't be controlled after Aetius was murdered.

You begin to see this system in the East, but they manage to somehow solve it with the "Bucellarii" system, invented by Stilicho in 404, and the East did not suffer as much from manpower likely due to an overall higher population.

As for the slavs overruning the Danube, that was a result of the earlier Huns under Attila, where after the war of 447 the Danubian Limes were more or less abandoned. Said limes were restored in the 450's460's, but comparatively would never be the same level of defensive capability as they had had in 445/446, prior to the second war with the Huns.

[Manuel I Komnenos]

12 millions is too much. Even the start of 20th Century there was less at Anatolia.

In 1025 the empire encompassed Asia Minor reaching as far as Antioch to the south and the province of Vaspurakan to the east, as well as much of the area south of the Danube (including Bulgaria). For such a massive area and considering the golden era Byzantium was experiencing, it's not an extreme number.

[Magister Militum Flavius Aetius]

Byzantium 1025-1045

[Kitsunegari]

What I've read suggests that a major advantage of the ERE was a "semi-hellenized" population of central Anatolia around modern Konya that provided many troops, Isaurians I guess? The major recruiting area for the WRE was Illyria, which was frequently lost to migrating tribes.

[Magister Militum Flavius Aetius]

Umm... Illyria was 1. Not Frequently Lost and 2. Not the main recruiting ground, other than in the mid-3rd thru early-4th century.

The East had the advantage of a higher population, and the landlords weren't nearly as reluctant to give recruits when it came time for the draft. The Isaurians in Seleukeia had actually never been really conquered, and became a nuisance in the 470's which resulted in a Military campaign which brought them under East Roman Control. They used this to their advantage by creating Numerii of elite Isaurian units.

Also, the East was heavily "Romanized" but there was a heritage of "Hellenic" culture that remained, but the East was certainly not still "Hellenic."

In the West, beginning around 390, you see a massive increase in the use of an "aedoratio," where the landowners paid a large sum of Solidi rather than sent their laborers to serve in the Army or public office. This is what caused the manpower problem, and with the collapse of any incentive to serve (Civic Virtue in the Republic, a Higher Social Standing/Citizenship in the Early Empire) people just didn't see any reason to.

[Kitsunegari]

So I guess the West shifted to primarily barbarian recruits after the accession of Constantine? Illyria and north Balkans being associated with Diocletianic era that would make sense. Theodosius was from Spain, but many of his officers were barbarians. I'm less familiar with ERE commanders' backgrounds, Narses seems to have been Armenian, Maurice maybe Thracian. It seems that they also were able to employ very effective barbarian units, mentioned as "Huns," Heruli, Sarmatians, and even Vandals after they were defeated.

[Magister Militum Flavius Aetius]

Well there was an issue with manpower, but the west didn't shift to primarily barbarian recruits until the time of Stilicho and Constantius III. Most of late antiquity saw barbarians serving as Roman soldiers - not foederati - but the Romans had always had barbarians serving as Roman soldiers. The problems arose when the Barbarians served as Barbarians in Roman armies and as Roman allies - this wasn't that bad until the se "allies" were foederati on Roman soil, rather than on the other side of the permeable limes.

The usage of Foederati themselves increased after the Fall of Africa - notably at Chalons - and during the Fall of the West after Aetius' death. The Eastern Romans capitolized on Foederati and Bucellarii, and their heavy usage of mercenaries supplemented their Roman Infantry, but they were able to maintain a decent balance until after the Komnenian Dynasty, after which there were almost no Roman Soldiers other than militia. Narses, Belisarius, and others all used large numbers of Foederati.

[Kitsunegari]

Yes I think the barbarians, even rebels like Alaric, saw themselves as Roman soldiers rather than invaders as is commonly believed.

[hellheaven1987]

Valentinian III did try a last ditch of effort by attempt to reintroduce militia system, failed nevertheless.

WRE during 5th Century was largely relied on a system similar as Byzantium theme system anyway, except its base organization unit was not province, but settlement. The same system would be the backbone of Merovingian military (chief reason why Clovis I proclaimed every race would exercise its own laws in its settlement, as that was how WRE did) even up to Gregory of Tours' time (himself claimed knowing a person who served in a Roman regiment that could trace back before the collapse of WRE).

[Magister Militum Flavius Aetius]

He didn't try a last ditch effort to re-introduce the militia system, the Novella Valentinianus 9.1 (14th June 440) issued a decree that said Citizens were once again allowed to ear arms - a right that had been taken away in 364, but a law that was probably not followed. In it he describes Sigisvult's reorganization of the town Vigilium and it also allowed citizens to keep the equipment of a slain enemy.

Frankly, all this did was really promote the bucellarii and foederati employed by landowners, rather than bring a martial spirit and roman militia to the citizens of Italy.

Gregory of Rours was referring to what he called a "Ripuarian Frank" - a group of Franks that did not exist. The Riparienses garrisons on the Rhine were intact and fully garrisoned by Alemanni and Franks during Aetius' time, as the systemw as so firmly established it was almost impossible to be overrun and assimilated - we also see this in Noricum before the time of the Vita Severini. These "Ripuarian Franks" were Ripenses/Riparienses units, and they gave Aetius an "arm" of authority for which to control the Salii on the Left Bank, and recruit Right-Bank Franks and Alemanni for manpower. The man Gregory knew was likely a soldier of the Rhine Frontier under Chlodio, and the unit extending back to Roman times likely was a slight exaggeration.

The system in the West was not a Theme System though - Each border province had Limitanei Garrisons to respond to incursions (more similar to the earlier Acritae), and large Field Armies to surpress usurpers, and later on, respond to incursions. Eventually, this did devolve into almost a "Theme System" where the Limitanei could no longer be recalled to campaign outside of more than a short range of their home base, but there was still the field army (notice I said the - Aetius had to cut the others entirely after 439).

As for the foederati, people often misunderstand what this meant - the Goths of Aquitania, the Burgundians of Sapaudia, and the Franks of North Gaul did not seek to establish independent Kingdoms, but wanted to become part of the Roman Empire. When they "rebelled" and besieged towns like Arras and Arles, they did not want to capture them, as they knew they would be unable to hold them, but sought to use their 'Roman Forces' to gain higher political status.

In the late 440's you begin to see a trend of Barbarians trying to keep Imperial Cities - notbale Chlodio's Franks, but they didn't start demanding the same status as Gaiseric as "Socius et Amicus" until after Aetius' death, when they knew Rome no longer controlled them, but they controlled Rome.

[Basileos Leandros I]

Even though Diocletian and Constantine managed to create a provincial/administrative reform, we can only talk about proper "themes" around the 7th century. Pretty much after Heraclius the theme system soon became the administrative division.

[Magister Militum Flavius Aetius]

That's true, but you can see the evolution towards a Thematic administrative (And somewhat military) system as early as the 4th/5th century.

[Dracula]

Who wants to see the Byzantine Empire today, has to go to Thessalonica. The entire place is ... I was struck. It's full with surviving Late Roman Empire buildings, enermous rotondas, triumphal Arch, walls, forum and what not. To top it up, all churches in the city are like cut off from a book from the time, with draperies(curtains), whatever you see on the old miniatures and icons is there. And to knail the entire thing, the Cathedral of st.Dimitrius ...probbably they took the model from it for the buidings in RTW 1. ing fascinating. Allthough the greeks don't screw, just drink. And there is this naval road avenue, where all caffes look at the bay which is enermous. And yeah, almost forgot, the new buildings in the centre have byzantine architecture, are modelled upon... Was even wondering how all this can have survived. But after all, it was the second city in the Eastern Empire.

To top it up, there ARE greeks with blond hair, white skin and light eyes. There was a boy, .. thought it was Apollo. At least understood where they got the idea for those statues. But unlike then, that boy didn't have an idea why someone may be interested in him. Eastern brainwashing.

[The Noble Lord]

It's nice to the map of the Byzantine Empire at its peak, during the reign of the Basil II, it's still unbelievable after this many years to understand how it
was possible to ruin everything and to lose this only 40 something years later at Manzikert.