Norman said:
So we're looking at what as a POD?
I say we go with Aetius and Attila. If you can keep the Western Empire and the Huns allies, Rome should be able to weather the storm, with some good diplomacy. Before I continue, I would like to curse accidently hitting the right combination of keys that totally erases your post (and the article of Murphy's law that states that you'll only do that when you've nearly finished). Consider them cursed. Friggin 'A.
Here's a good read on how the whole collapse went:
http://www.ucalgary.ca/applied_history/tutor/firsteuro/invas.html
In summation, at the time of Attila:
Britain was long gone, with no chance of being retaken in the near future. The Visigoths were in western Gaul (Aquitaine) and were in the process of moving into Hispania. The Franks were in Northern Gaul, near the Rhine. The Burgundians were in southeastern Gaul, with the Alans to their west. Pannonia was under Ostrogothic control. Hispania was mostly Roman, with the Suevi in the northwest. North Africa was under control of the Vandals, who had just left Hispania and were getting ready to raid Sicily and pillage Rome in a few years. The Balkans were under control of the Eastern Empire. Everything else in Europe was under the control of the Huns (in theory).
So, to save the Western empire, a few things have to happen:
1) Keep in good with the Huns, use them to beat the snot out of the other troublesome tribes.
2) Attila has to live longer. His empire isn't going to last long after his death. If he lives long enough to name an heir, I give it a generation. With a pro-Roman Attila (pro Western Roman, that is), Rome won't have to fear the Huns at the height of their power. Afterwards, they won't be much of a threat.
3) Aetius has to live longer. He was far more capable than Emperor Valentinian and his assassination led to Valentinian's.
3) Some of the tribes have to be redirected from attacking Rome.
The first two are easy. The third is a bit more complicated. The empire is going to have to deal with serious short term losses. To minimize them, there's gonna have to be some really good diplomacy going on here. I think Aetius and Attila (both had a good grasp of the political situation and how to handle it) could pull it off. To this end, I propose that:
1) The Franks be redirected to Britain. We'll have the Roman Celts of the island (who still controlled most of the former province) ask for their assistance against the Angles, Saxons and Jutes. This will likelyhave the added benefit of keeping some of the Romanization of Britain alive. The Angles, Saxons, and Jutes almost completely replaced the Romanize population, unlike the Franks, both Goths, and the Vandals. Replace them with the Franks, and the culture will be more Roman.
2) The Vandals be redirected to Hispania and/or the Eastern Empire. They were, after all, just recently in Hispania and the East was, after all, wealthier than the west. I say that Aetius offers them land in Hispania.
3) The Burgandians and Alans be taken out.
4) The Visigoths be forced out of Gaul, while allowing them into Hispania. This will leave Gaul almost entirely under Roman control, while dividing Hispania between the Suevi, Vandals, Visigoths, and a few Romans. Keep the Romans, Suevi, and Vandals on the same side, and the Visigoths should have their work cut out for them.
5) The Ostrogoths be directed into Thracia, instead of Italia.
The Huns, of course, are allied with the West and will probably be extorting the East for everything they can get. The East will likely be a bit more willing, as they now have to deal with the Ostrogoths and Vandals at the same time.
Aetius will be very popular, having played so many of the tribes against each other and saving the empire for now. If we don't go with Attila marrying into the Imperial Family scenario, one of Aetius' sons will likely become the next Emperor.
The Emipire will control Italia, as well as most of Gaul. North Africa and Hispania will only be weakly held, as the tribes there will divided, spread out, and/or fighting each other. The time would be ripe for the Empire to expand into either, though whether the Legions would be in any shape to go campaigning, I'm not sure. Britain isn't likely to be regained, since the Franks were pretty formidable, and were coming to the aid of "Romans", so the Empire would have no good reason to attack them anyway.
Next, I'll takle taking down the East.