All revolutions — political, cultural, technological, what have you — depend on communication. The better and faster the means of communication, the greater the likelihood of the revolution succeeding.
Successful “revolutions” in the Middle Ages, for instance, were cultural and technological. Before the printing press, the realm of ideas was limited to the clergy and a few literate aristocrats. Thus, the speed of communication was very slow; revolutions had to happen from the ground up, with some guy traveling to a distant land and reporting back “that’s how they do it over there.” Which is why you see academic tomes covering things like “the 12th century renaissance” and “the evolution of courtly culture.”
Political revolutions didn’t really happen. Even if a thinker — Nicholas of Cusa, say — had a radical political program, by the time his hand-copied manuscript got circulated to enough aristocrats who were willing to field an army to implement it, conditions on the ground had changed so much that nobody was willing to risk it. Thus, there were only three kinds of medieval “political” “revolutions” — the “charismatic cult leader” type, the “society-wide riot” type, and the “Game of Thrones” type.
The GoT type should be obvious — swapping one branch of the aristocracy for another. Your rebel lord didn’t have a coherent program to be a better king than the guy currently wearing the crown; all he had was a sufficiently large group of similarly disaffected nobles, who felt they had less to lose by rebellion than by maintaining the status quo. This was the main source of turbulence in the Middle Ages, and the results could be spectacular — English kings never lacked for opportunities to go to war in France, and vice versa, because there was always some malcontent local lord willing to give the other guy a shot. The stuff about tennis balls and the Salic Law makes for fun theater, but there’s really no political philosophy involved at all.
“Charismatic cult leader” rebellions are much more fun to read about, and you still can’t do better than Norman Cohn’s classic The Pursuit of the Millennium for all the gory details. They were probably more fun to live though, too — until you got to the burning at the stake part, anyway — because the CCL’s main appeal was overthrowing social convention, which in the Middle Ages always quickly devolved into sexual license. Of course they had “theories” about overthrowing social conventions, but they all boiled down to “we kill off all the sinners while sleeping around as much as we want, and then the world ends.” Here again, no elaborate justifications are needed. By the time the theologians start picking your doctrines apart, you’re getting racked by the Inquisition; by the time the rest of the country hears about it, your head is on a spike in a public place.
So, too, with the “society-wide riot” type of rebellion. Guys like Wat Tyler had a program, sort of, but it didn’t extend much past “get the nobles off our backs by burning the debt records.” No deep thought here either, and so they’re useless as precedents — Wat Tyler still popped up in English folk mythology, but nobody would cite “Wat Tyler’s legacy” as a reason for attempting to overthrow the legitimate government. See also the Jacquerie in France, where chaos for chaos’s sake was raised to an art form.
When they fail, all these types of rebellion fail for the same reason: Lack of communication. Yes, even the GoT ones. Because communications were so slow, and the literate population so small, all gripes were basically local gripes back then. We might know what, specifically, a guy like Wat Tyler wanted, but what reason does the rest of the country have to join him? Ditto the crazy cult leader, whose “ideology” was probably pretty appealing if you had the chance to hear it… which, of course, you never did, unless he or his movement passed directly through your region (in the medieval sense, meaning “passed through the next village over,” not “passed through France”). Ditto the rebel lord, who needed to convince the nobility as a whole, and at least some of the peasantry, to support him. One of the main reasons Percys and Howards were forever getting themselves beheaded in England was, their rebellions were too obviously about obscure Scottish border stuff. You need national appeal to effect real regime change, and communication conditions in the Middle Ages guaranteed that would almost never happen.
The printing press changed all that. Now local gripes could quickly be made national gripes. Quickly, of course, is relative, but in the 1530s the speed of information reaching the backcountry could produce something like the Pilgrimage of Grace, a set of local gripes against Henry VIII’s reformation that quickly became quasi-national. By the 1630s, stuff like the Five Knights’ Cases and the Ship Money controversy, which would’ve been local affairs a century and a half before, helped bring down the King. He who best mastered his era’s communications was the victor.
Not coincidentally, the print media age is also the age of ideology. For the first time, would-be rebels could set out a clear vision of how they wanted the world to look, and a coherent program for getting there. For the first time, “reform” is forward-looking, rather than a return to the past. The Pilgrimage of Grace is instructive here, as a transitional moment. The literate leaders, like Robert Aske, were “forward-looking,” in that they could see the need for structural reform and debate at least some of the philosophical issues surrounding it. The illiterate peasantry, by contrast, were backward-looking — they just wanted their robes and candles and pretty pictures back. (Note that Aske himself ended up hanged in chains).
Henceforth, no rebellion could ever hope to get far off the ground without a coherent ideology, and a convincing picture of what the world would look like because of it. Improvements in communication facilitated that, both in getting the word out, and refining the arguments of the would-be revolutionaries. There are a million examples of would-be revolutions failing in the modern age, but the nearest and dearest to our hearts is probably the failure of Leftism. They had the vision, all right, and they spent the century between The Communist Manifesto and the dawn of the internet refining their arguments. But, of course, their initial successes doomed them — instead of communicating with the masses, they now only communicate with each other, with the inevitable deterioration of their logical, historical, and rhetorical facilities. And that’s why the Alt-Right is running rings around them.
That should be a warning to the Alt-Right, though. As of now, their “program,” if they can even be said to have one, is backward-looking. It is both true and obvious that the Enlightenment has failed, that Equalism is wrong, and that “democracy” as currently practiced is a suicide pact. But… what will we replace them with? Nobody really wants to live in the Middle Ages, you know — not even authors of fantasy novels and cosplay enthusiasts. It’s crucial that we communicate what the world will look like once we’re done with it. Otherwise, we’ll have lots of fun, but it’ll be Wat Tyler-style fun… and probably with the same result.