A good article by Bret Devereaux, a Roman historian, refuting the simplistic claim that "Hard times create strong men, strong men create good times, good times create weak men, and weak men create hard times":
Hard Times Don't Make Supersoldiers
“Hard times create strong men, strong men create good times, good times create weak men, and weak men create hard times.” The quote, from a postapocalyptic novel by the author G. Michael Hopf, sums up a stunningly pervasive cyclical vision of history. The idea, which I have termed elsewhere “the Fremen Mirage” after the science fiction novel Dune’s desert-dwellers, posits that harsh conditions make for morally pure and militarily strong people, while wealth and sophistication make for decadent societies and poor fighters. Dune is just one example of the numerous speculative fiction novels that use the idea, from the Conan stories to dreadful Star Trek episodes. It is so common as a popular theory of history and military power that it has spawned (like most bad ideas) its own genre of internet memes.
It also infects modern strategic thinking, especially about non-Western foes. Perhaps most famously, after the attack on Pearl Harbor collapsed complacent notions of American superiority, the Allied intelligence community swung wildly from the belief in the Japanese as weak and unmanly to notions of how the harsh conditions of training and life in Japan had churned out apparently unstoppable supersoldiers. More recently, the same trope has reemerged in the invincible insurgent, whose upbringing supposedly renders him immune to the deprivations of combat and campaigning. As the University of Birmingham researcher Patrick Porter notes, “commentators have claimed that Iraqis, Afghans, Yugoslavs, Amerindians, Somalis, Turks or Japanese are particularly predisposed to war”...
It makes a degree of intuitive sense. Westerners subject their soldiers to harsh conditions to prepare them for the rigors of combat, so why wouldn’t whole societies work the same? Shouldn’t people (although the trope often specifies men) who’ve dealt with hard conditions all their lives make the best fighters, in contrast to the flabby, decadent inhabitants of the glitzy cities?
Except that’s not how things turn out. The divide between supposedly decadent civilization and its supposedly hard and uncivilized opponents reaches back to the development of farming and the state. Early farmers, with their higher population density, seem to have outcompeted their nonfarming neighbors. It seems that in many, perhaps most, cases, it was farmers who expanded, rather than the practice of farming itself, pushing the surviving nonfarmers onto more marginal lands. Likewise, early states, with their complex and specialized hierarchies, generally outcompeted their nonstate neighbors. Urban communities first dominated their countryside and then expanded that dominion outward. Nonstate peoples were often set with a dilemma: develop their own state institutions in order to compete with the brutal efficiency of state violence, or else find themselves violently incorporated into the tributary networks of expanding states. By and large this process was one in which the “strong men” created by “hard times” lost, again and again.
This doesn’t change in the shift from prehistory to history. Occasionally the frontiers of the zones of urbanized, stratified state-societies broke. Given enough attempts, nonstate people might eventually win. But most of the time, it was the urban armies that were doing the pillaging. Take Rome’s frontiers, the limes, as an example. Rome is, after all, the byword for decadence and decline in Western discourse. Western cultural memory fixes on the Goths, Vandals, and Huns who broke the Roman frontier, but it is quick to forget the rather longer list of nonstate peoples broken by the Romans. The Samnites, Cimbri, Teutons, Ambrones, Helvetians, Eburones, Arverni, Celtiberians, Lusitanians, Pannones, Dalmatae, Catuvellauni, Iceni, Marcomanni, Quadi, Iazyges, and all of the other “hard” peoples crushed under the Romans do not become household names. Most successful large states in history can boast similar butcher’s bills.
Of course, there are exceptions, like the early Muslim conquests, the Seljuk Empire, and of course the Mongols, which overthrew long-established and long-successful empires. The horse nomad was a powerful force for a time—but one often incorporated into the armies of conventional states. But the victims of empire, out there on the fringes, left no memoirs of the disasters inflicted upon them; when the so-called barbarians won, however, it produced entire literary genres lamenting the fall of the great cities.
But if this historical trope is a poor guide to either history or modern strategy, where does it come from and why has it proved so persistent? While there are quite a few explanations for the success of nonstate actors (most historiographical traditions have at least one), this mirage has its roots in the Greek and Roman ethnographic tradition.
The literary trope goes back at least as far as Herodotus and his account of the ill-fated invasion of the Scythia by Darius I, king of Persia, in the 6th century B.C. Herodotus presents the Scythians as ruthlessly expedient, relying on a scorched-earth campaign and their own relative lack of fixed settlements to exhaust the Persian military juggernaut. Prefacing that narrative is an ethnography of the Scythians, which presents Scythia as a hard, cold land, unfit for farming—but the nomadic life it forces on the Scythians, Herodotus writes, makes them “unfightable and unapproachable.”
Except Herodotus never went to Scythia, and his knowledge about Scythian customs, culture, and even local geography is uneven at best. But, as observed by the historian François Hartog in his landmark The Mirror of Herodotus, none of that matters, because accuracy was never the point. Rather, Herodotus is using the Scythians as a prelude to the Greco-Persian wars, mirroring the Greek victory (which will also involve strategically giving ground). Herodotus’s narrative was never about the Scythians or the Persians but about the Greeks, an exercise in self-definition for a people who had not generally thought of themselves as a unified whole. That is the mirror of Hartog’s title: The Scythians and the Persians serve as foils against which Greek identity can be defined.
Likewise, in the Latin tradition, the barbaric “other” might be marshaled for political advantage or social self-criticism. By the time of Julius Caesar’s writing in the 1st century B.C., the trope of hard-fighting barbarians whose ascetic way of life made them both morally and martially superior was firmly set enough that Caesar could lean on it as a shorthand to build up his own military accomplishments...
Caesar is about to crush these Gallic and German “supermen” with an army of excessively civilized Italians who are not only exposed to all of the things that tend to “effeminate the spirit” but in fact are responsible for producing those things. Indeed, of all of the Gauls, it is not the warlike Helvetians or Belgae who give Caesar the most trouble, but the Arverni, who live in what is today Auvergne, France, right up against the areas of Greek and Roman settlement and right on the trade routes bringing supposedly effeminating Mediterranean goods and culture into Gaul. Caesar knows this, of course, but his Commentaries is a political document, and he also knows good politics: tapping into stereotypes his audience already believes to build up his military success. Better to brag about defeating the Helvetians, Belgae, and Suebi, which no Roman had done before, than the Arverni, who had fought and lost against Rome once before. Accuracy was beside the point.
Perhaps the most influential ancient work of this sort is Tacitus’s Germania, written in 98 C.E., which sets out to describe the customs and society of the peoples across the Rhine from the Roman frontier. In brief, Tacitus describes the Germans as indigenous to their lands without being intermixed with other peoples, contemptuous of wealth, beauty and luxury, singularly focused on military virtue, pious, monogamous, and chaste, if unsophisticated and uncultured—a product of the harsh lands they inhabit. Again we have our “strong men” molded by hard lives.
Except the Germania is not about the Germans at all, but a critique of Roman decline in the tradition of the Roman historian Sallust, thinly disguised as ethnography. Tacitus’s tone in his writing overall is one of frustrated discontent at the moral decay he saw in Rome, and it is nearly impossible not to see this sharping the Germans of the Germania.
Tacitus himself almost certainly never traveled north of the Alps, did not speak any German, and only possessed, at best, secondhand information about any German customs. Instead, he constructed his Germans as a foil for what he saw as Roman moral decline, with German virtues to match perceived Roman vices. Lest Tacitus’s dire moralizing be taken too seriously as evidence of an actual decline, it is worth noting that he was writing at the very beginning of one of Rome’s best centuries and an unbroken string of five capable rulers. Decadence and decline would be very slow in coming, indeed.
This vision of ancient Germans and Gauls was revived in the early modern era (Tacitus’s Germania, lost during the Middle Ages, was rediscovered in 1425) and pressed into service as part of the intellectual foundation for 19th-century nationalism, where it congealed with the so-called scientific racism of the era. Where the ancients believed barbaric strength and decadence to be caused by place, 19th-century nationalists saw it rooted in race, citing these ancient accounts as proof that this or that European racial group had always been superior. The role of decadence was explained by “racial mixing.”"
tl;dr: Basically this claim was repeatedly made in antiquity by writers wanting to criticise their own supposedly decadent societies, but in reality civilised societies ("weak men") crush barbarians ("strong men") a lot more often than the reverse, and in more modern times the claim has been revived for political reasons (often by people wanting to criticise their supposedly decadent societies)
