Matt Quinn said:
How long do y'all think it will take for the following AH empires, under realistic conditions, to collapse from overextension? What would result?
1) The Domination of the Draka
2) A Victorious 3rd Reich
3) The Soviet Union w/ "limited" containment policy (as advocated by Kennan)
4) The Soviet Union with no containment policy at all
5) A Roman Empire with frontiers on the Oder
6) Persian Empire with all non-Anatolian Byzantine territory
7) Islamic Caliphate w/ victory @ Tours
8) Islamic Caliphate w/ victory @ Constantinople
9) Mongol Empire if that Khan didn't die (thus sparing Europe)
10) Spanish Empire after victorious Armada landing
11) British Empire crushes American Revolution
1. A realistic Domination would either just be a bigger South Africa, or would never industrialize, so eventually being dominated and colonized by more advanced nations, or, in Ian's scenario, would bite off than it could chew, and be totally defeated ala Nazi Germany. By the time the Domination is strong enough to win, you're in a parallel reality where different laws apply.
2. Victorious Nazis might last different lengths of time, depending on how pragmatic Hitler's successors are, on how much opposition they face beyond their borders, and on how big their empire is. A Nazi Germany that conquered all of Europe out to the Urals, and had the United States as an enemy would probably be very overstretched, indeed, and at best could make it to the late '90s or around now before imploding, probably with nuclear death throes. With poor leadership after Hitler, it wouldn't even make it that long, figure maybe mid-'70s. If America is more neutral or isolationist than hostile, figure it could hang on longer, but will still self-destruct by the second decade of the 21st century at the latest. A Nazi Germany that does not invade Russia (say Hitler drops dead in late 1940, frex) has a much longer lifespan, perhaps even measurable in centuries, if the leadership is pragmatic enough, not that I think pragmatic Nazis are all that likely.
3. Limited containment will mean less competition for the Soviets, but they have still taken staggering losses in WWII, the economic system still doesn't work, and Stalin has still discredited Communism to most everyone who lives under it. The areas that the Communist Bloc would be likely to absorb with limited containment are not especially productive or useful, and would cost resources to prop up, so I think you're looking at a lifespan of about the same length, or, at best a decade or two longer. What _is_ possible is that such a situation may give the Soviet Union the opportunity to reform itself without collapsing, so you end up with the collapse of Communism, but a USSR that holds rather shakily together.
4. Hmmm, essentially a Bob Taft US. Well, I'm guessing the Soviets would be able to either absorb or trade with some much more productive regions, then. It might last several decades longer, and fall harder, but I doubt it will ever make it to its second century, and probably not even get close. After all, a command economy _still_ doesn't work.
5. The Romans will definitely last longer with fewer and weaker barbarian invaders. No empire lasts forever, though, and the problems of economic decline, succession, and probably civil war all still exist. So, too, do all those plagues that so lowered the population in OTL. I would guess that without barbarians, the Fall of Rome takes a totally different character - by 650 or so, the Eastern and Western Empires are different in language, customs, types of Christianity, and they are probably starting to fight. From there, it's only a matter of time before other regions break off, with Britain, Germania, North Africa, and Egypt all being possible micro-Empires of their own. OTOH, the mystique of the universal Roman empire means that it is just as likely that somebody eventually reuintes the Empire someday, giving us the same kinds of cycles you see in Chinese history.
6. The Persians fell apart for reasons having little to do with imperial overstretch, and they will still be operative no matter how big the Persian Empire gets. A bigger Persia may be able to resist the the Moslems, assuming they are not butterflied away, but civil wars among the leading noble families will still crash the Persian Empire before about 700. OTOH, it might, like the Roman, get revived, perhaps under a Zoroastrian, Turkic dynasty.
7. Again the disintigration of the Islamic Empire had little to do with overstretch, and everything to do with sucession problems, chronic political instability, and long communication gaps from one end of the Caliphate to the other, which is related to overstretch, but not the same thing. My guess is that it falls apart on the dot, but a bigger chunk of Europe gets absorbed into the Ummayad mini-Caliphate centered on Cordoba. Even this doesn't last, however, because that state was also chronically unstable and prone to civil wars between Arabs and Berbers. So, my guess is that the Moslems are eventually driven out of France and probably northern Spain, finishing the Caliphate as an empire, even if southern Spain stays Islamic.
8. The loss of Constantinople means that Islam gets further in the Balkans, probably a lot further. It might well induce the Russians to convert to Islam instead of Orthodoxy, though might also just stay Slavic Pagan instead. Either way, this doesn't lengthen the life of the Caliphate by so much as a day. It does mean a lot more small Islamic Emirates, Sultanates, Khanates, and so on, some of them damn strange ones by OTL standards. This will send the history of Islam in all kinds of cool, but unpredictable directions.
9. Again, the problems of the Mongols were not that a matter of overstretch in the normal sense, but rather of administration and dynastic instability. So, the Kha-Khanate will still break up into successor Khanates on time. Likewise, the Mongols will retreat from Western Europe and the Germanies pretty quickly. They always did hate forests. You might, however, get some pretty long lasting successor states in parts of Eastern Europe. Most of the ones in Russia and the Middle East fell apart by about the 1400s in OTL, so I'm guessing this happens in most Mongol-victory ATLs, as well. OTOH, a non-Mongol, but Mongol-influenced autocracy like Muscovy could easily appear in Central Europe, and last for a very, very long while.
10. My guess is that a victorious Armada does not lead to a glorious revolt ala Turtledove, though his book is a lovely one. Nor does it lead to a lasting Spanish Empire. Like as not, overstretch still ruins Spain, and the Stewarts profit from it, eventually "liberating" England from Spanish rule. My guess is this happens by about 1610 at the latest. If the defeat of England leads to a Guise victory in France, and victory in the Netherlands (though I have my doubts), Spain might stay somewhat dominant in Europe down to the early 18th century, but only because its friends don't challenge it. Even the Guises, however, will eventually figure out that Spain is a lot weaker, and will eventually take advantage of that fact, bringing about the fall of the Spanish Empire. Anglophone settlement in the Americas, however, might easily be butterflied away, leading, depending on your preference in ATLs, to various Francophone Americas, or to America as a Third World backwater, possibly with a strong and prosperous Mexico. Or not, depending on how the butterflies flap.
11. Despite my affection for Irish culture, I don't really think the British would behave all that badly if they won the Revolutionary War. British behavior in Ireland stemmed from the early date of the conflict, its long duration with resultant bitterness on both sides, and the fact that the Irish spoke a different tongue, had different laws and customs, and, after the Reformation, followed a religion viewed, mostly accurately, as hostile to the Church of England. None of that is remotely the case in America. I would guess that a failed American Revolution would be followed by the quick establishment of local Loyalist governments, which would be oppressive for awhile, but would fairly quickly settle down to use their authority pretty responsibly. I think Sobel is pretty optimistic to have the CNA form by 1780, though it is possible. More likely is that the Younger Pitt allows, or even encourages, the formation of such a thing in the late 1790s or first decade of the 19th century. This means that British North America turns into a pretty nice place by the early 19th century, comparable to Canada in some ways, and to the United States in others. No doubt about it, the British Empire as such would be a lot bigger, and, with the wealth and industrial might of America to support it, would be very, very powerful, indeed. My guess is that it would not "fall" at all, but just slowly evolve into a federation of self-governing Dominions. Depending on what happened in the rest of the world, such a federation - backed by a host of traditions (some of them even authentic!), the mutual self-interest of its members, and the industrial power of North America - might last very, very long, indeed. Think centuries. Many centuries.