I'm thinking pretty generally about changes in economic systems, where one set of power structures and means of production gets swept away by a whole other one.

I'm thinking pretty generally about changes in economic systems, where one set of power structures and means of production gets swept away by a whole other one. Usually the participants of these frame them in cultural or moral terms, because it's easier to convince the lower classes to fight for you if you say "We're all on one side, we share a common culture, and there's this evil power over there that is a threat to our way of life." But if you look at who the sides are in the conflict, you can usually identify a specific declining economic system identified with one set of combatants, which is being overtaken by a new economic system identified with the other set of powers. (This is a common idea in international relations circles: you get wars when there's a change in the relative balance of power between states, such that each of them thinks they have a realistic chance of winning it.) Specific examples: Crisis of the 14th century paving the transition from the feudal era to the renaissance (and the development of market economies and mercantilism). Europe was depopulated by Black Death, the Hundred Years War, and the Wars of the Roses. This gave peasants bargaining power for their labor, and also meant that many younger sons of nobles stood to inherit property. As a result, an economy sprung up around trade and specialization, distinct from the feudal relations between lord and peasant. The catalyst for this was simply death; many of the old power players died off from the plague and subsequent wars, leaving those who didn't die off to rebuild the world based on current economics. American Civil War. This is usually framed as being about slavery, which it was. But it's often glossed over how much of this debate was actually a clash between two economic systems, the plantation South and the industrial North. When both sides were primarily agrarian, the balance of power favored the more fertile, slaveowning South. But as the Industrial Revolution progressed, its higher productivity a.) gave the North more economic power and b.) also raised wages there, so that it became increasingly attractive for slaves and poor whites in the South to migrate North and take advantage of the jobs in the factories. The 1850s was the crux of that, where U.S. politics still favored the South, but economics favored the North, and this disconnect led up to the Civil War. (Think of how the Supreme Court felt that the Dred Scott decision would settle the question of slavery once and for all, but it was nullified 6 years later under force of arms.) And of course, once the war started, Northern industrial might proved critical in winning it, in the form of factories and railroads. Italian & German wars of nationalism in 1871. (The American Civil War can also be lumped in with these, and to some extent the Napoleonic wars.) These are cases where an individual city-state within a broader ethno-nation (Prussia for Germany, Rome for Italy) managed to either conquer or convince enough of its neighbors to build a larger nation-state. This was driven by economics, along with changing military tactics. Rifles, railroads, gatling guns, and artillery gave benefits to large standing armies that required the resources of a larger political entity to maintain; meanwhile, industrialization and mass production gives larger economies of scale to larger markets. Those leaders who recognized this pushed for larger states, and it also gave them the means to conquer leaders who did not. (You could look at most wars from 1865-1917 as transitioning from colonial imperialism to industrial nationalism. The American Civil War, Italian Independence Wars, Austro-Prussian War, Franco-Prussian War, Meiji Restoration, Russo-Japanese War, WW1, and dissolution of the Ottoman and Hapsburg Empires all resulted in a well-organized, mostly ethnically homogenous, and industrialized states taking over former imperial colonies, largely on the strength of the military technology & tactics that such an industrialized nation-state could bring to bear. Contrast with earlier wars like the Mexican-American war or Napoleonic Wars, which involved a larger imperial power conquering a smaller one by virtue of superior numbers rather than superior technology.) We also have events like the Russian Revolution (1917) and Chinese Civil War (1912-1949), where the old imperial regime collapsed under its inability to provide for the populace's needs, but was replaced by Communism rather than Nationalism. The fall of the Soviet Union (1991) is another such event, replacing communism with (somewhat corrupt) market capitalism. I'd say that the biggest counterexample is the end of the Pax Brittanica and Britain's fall as a hegemonic power. You could argue that WW1 was the war at the end of that economic system, though, and many scholars say that WW1 was a direct result of Britain's declining industrial & military advantage as other Great Powers industrialized. That they were succeeded by their former colony is largely an accident of geography and shrewd U.S. actions in the first part of 1800s. Had Jefferson not made the Louisiana purchase, or the U.S. not prevailed in the Mexican-American war, the outcome of WW1 might have been very different.