WI: Crisis of the Third Century Kills Rome?

Define "kills Rome". Do you mean breaks apart into separate states, completely collapses, or? Because that has a large effect on what happens next. Arguably the breakup of the empire into three is what saved it oddly enough.
 
Define "kills Rome". Do you mean breaks apart into separate states, completely collapses, or? Because that has a large effect on what happens next. Arguably the breakup of the empire into three is what saved it oddly enough.
Into separate states mainly, but I would not mind a complete collapse scenario
 
Into separate states mainly, but I would not mind a complete collapse scenario
Okay. Well, truth be told I'm not sure how viable a separate Gallic Empire would be (I'm of the opinion that if the legitimate roman empire collapsed, the Gallic Emperor (assuming the empire was stable enough) would come in and sweep up at least Italy. But let's assume it is:

It isn't too difficult to make the Palmyrene Empire independent. The Roman Empire was in no position to challenge Zenobia until Aurelian, and even then Aurelian was kind of a special talent to be able to re-unite the empire with such speed. So, basically, what you'll have most likely is an independent Palmyrene Empire controlling essentially what the eastern roman empire controlled minus the Balkans (though possible Byzantium, if only to control the Bosporous Straits). They should be strong enough to hold off against the Sassanians.

The best scenario for the Gallic Empire is that Posthumus remains its head for as long as possible. That should be easy, since his death OTL is easily preventable. Since it didn't appear he had any interest in invading the legitimate empire and making good his claim to the throne (at least, not when he had the perfect opportunities to do so), it leaves enough of a window open to exploit a potential collapse of the legitimate empire, which I think is necessary to achieve this Balkanization.

Now on to the legitimate empire: Have a complete collapse of the Balkans frontier. Basically, the best scenario for this is preventing the battle of Naissus and then having either Gallienus or Claudius Gothicus have a crippling defeat. This blasts the floodgates wide open for the goths to continue raiding Greece and the Aegean, and with another victory, to completely overrun the Balkans-it helps if the Juthungi break through Italy at around the same time and sack Rome (which of course was relatively undefended until Aurelian built his walls). This would throw the empire into chaost, and you could see the Balkans completely out of Roman control.

So what you have in that situation then is:

  • Roman successor state in at least North Africa and Sicily, and possibly Italy depending on what goes down there
  • Gallic Empire controlling Spain, Gaul, and Britain
  • Palmyrene Empire controlling all of Roman Asia, and probably (especially if the goths overrun the Balkans), Byzantium and the Aegean to try and counter the Goths who would be wreaking havoc on the Anatolian coast as well
Now if you want a complete Roman Empire collapse....that's really simple. Don't have the Roman Empire split. The split allowed them to prioritize where to defend-Gallienus could focus on stabalizing the Danube, Posthumus on the Rhine, and Odenathus and then Zenobia on the eastern frontier. Without this, the empire simply can't deal with all the threats at once. If Odenathus doesn't defeat the Sassanians after Valerian's defeat, it's possible that all of Asia could be swept by the Sassanians in the following years. Couple that with a series of emperors on the Rhine and Danube who are not Posthumus and more interested in pressing their claims and marching on the reigning emperor...well then you have the weakening of those respective frontiers leaving it rife for massive breakthroughs.





Really, it's something of a miracle the Roman Empire survived the third century.
 
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