Interesting thought - the Germanic remnant in Scandinavia might be compared to the OTL Celtic remnant in Hibernia/Caldedonia. Depending on events, the Germans might be similarly thought of as sort of a mournful, remnant people on the fringes of civilization.
The population of the Empire at its height was 65-70 million.Errr, the OP says that the conquered area is up to Vistula-Dniester line which (including Dacia) contains a significant amount of tribes and towns...
Alright, if not become doubled, maybe increased by one and a half...
The reason for "barbarization of the army" is because Barbarians simply made better soldiers and were more commonly available than Roman citizens who tried to avoid service, not because the Germans were genetically better at soldiering. So yes, I can see that happening.Does it? Why wouldn't the frontier armies just became Sarmatian/Slavic/whatever, instead of Germanic?
Errr, the OP says that the conquered area is up to Vistula-Dniester line which (including Dacia) contains a significant amount of tribes and towns...
Alright, if not become doubled, maybe increased by one and a half...
Whoops, missed that.
I suspect it's ASB, though. After all, despite repeated incursions, they never even managed to conquer Caledonia - and the area this envisages is Caledonia multiplied by ten or twenty, presumably ending at a "Hadrian's Wall" from the Baltic to the Black Sea! It sounds prohibitively expensive, especially when the legions could be more profitably employed to attack somewhere like Parthia, where the natives were worth robbing.
Another thought... if the Empire does split something like OTL, who gets the new provinces? Dacia to the ERE and Germania to the WRE? because, that would give the WRE a very short border, something they badly need. Or does the WRE get Dacia as well? Probably not... that would make them too dangerous to the ERE!.
Personally, I think Teutoburg is a bit overrated. At the equivalent battle in Caledonia, Mons Graupius, Agricola won a smashing victory, but it made no difference because the area just wasn't worth the expense. And the Romans did sucessfully invade Germany even after Teutoburg, but again with no lasting consequences. The legions were getting into areas where the rewards of victory were too low and the cost too high.
Could the cost problem be negated by granting massive land estates in Germania to legionaires that volunteer to a campaign there. And by massive I mean at least triple what the legionaires usually got. That would get some folks eager to go there, even if there won't be as much loot.
I'd agree with more concentration on Africa rather than Europe.
The Red Sea (both sides) was rather civilized, if Rome could expand their influence with the semites down there it would be a lot more valuable than European forest. Even directly. Indirectly it'll bring them more into contact with India which...would be very profitable.
That would mean that the population of Germania+Dacia is atleast 60 million.Errr, the OP says that the conquered area is up to Vistula-Dniester line which (including Dacia) contains a significant amount of tribes and towns...
Alright, if not become doubled, maybe increased by one and a half...
With the Romanization of the Germanic tribes, the Slav-Balt-Scythian barbarian peoples would in all likelihood have lacked the demographic base to establish a lasting conquest and permanent substitution of ruling elites in the Romasphere.
My reasoned expectation on this subject is that the annexation of northern Europe, all the way to the msot favorable Vistula-Dniester border, would have not by itself prevented the political instability of the Roman Empire, but it would have prevented or greatly lessened the severity of the fourth century crisis, and in any case stopped it from causing permanent political distintegration of Europe into nation-states.
With the Romanization of the Germanic tribes, the Slav-Balt-Scythian barbarian peoples would in all likelihood have lacked the demographic base to establish a lasting conquest and permanent substitution of ruling elites in the Romasphere. Even if the Empire had temporarily broken out, it is quite likely that it would have entered a China-like dynastic cycle, and sooner or later the relatively intact parts of the Empire would have reunified it (say the *Justinian reconquest is fully successful ITTL), and in the worst case the Huns would have just managed to put a dynasty of their own on the Imperial throne for a while, with Rome assimilating its conquerors rather than the other way around.
It remains however quite possible that the WRE-ERE division could have become permanent, owing to the Latin-Greek cultural divide fueling it.
IMO, the all-important steps to prevent the downfall of Rome were, in rough order of importance:
1) Conquering Germania
2) A more stable political constitution
3) Conquering Parthia
4) Balancing the power of the landowners and of the professional army with other components of the ruling elites.
Agree with all of the above, except I don't see why Rome needs to conquer Parthia/Persia when it could just as easily defang the looming threat of another empire by conquering and consolidating its hold on Mesopotamia -certainly a relatively easier task. To me, it seems that would be enough to ensure that Parthia/Persia is no longer a major military threat to the integrity of the empire. With Mesopotamia securely in Roman hands, the outright conquest of the Persian hinterlands would be desirable, but no longer necessary.
Incidentally, it seems to me that if you're really wanting to strengthen Rome, the best place to do it might be Africa. If they can conquer present day Morocco and northern Algeria, they have a secure border on the largely uninhabited Sahara Desert - unlike Europe where basically however far they go there'll always be another tribe of Barbs behind the last one. If those areas can be conquered and assimilated, they could supply valuable military manpower. Later on it was chiely Moroccan manpower that conquered Spain and held it for several centuries against Christian reconquest. As usual, though, the short term profit wasn't great enough for anyone to bother.
With the Romanization of the Germanic tribes, the Slav-Balt-Scythian barbarian peoples would in all likelihood have lacked the demographic base to establish a lasting conquest and permanent substitution of ruling elites in the Romasphere.
Agree with all of the above, except I don't see why Rome needs to conquer Parthia/Persia when it could just as easily defang the looming threat of another empire by conquering and consolidating its hold on Mesopotamia -certainly a relatively easier task. To me, it seems that would be enough to ensure that Parthia/Persia is no longer a major military threat to the integrity of the empire. With Mesopotamia securely in Roman hands, the outright conquest of the Persian hinterlands would be desirable, but no longer necessary.