One of the premises of the EU is that such a regional union fosters cooperation and peace, truce in contrast to their bloody history. Yet there are detractors from such oversized unions (ahem, Brexit)—of which breakdown-of-nations is one, claiming that on the contrary, it is the mega-unions waging wars eternal. Is it possible to keep the peace without having to resort to hegemony?

The Kohr argument: there are going to be wars anyway. Let them get it out, don't stand in their way, but keep them as skirmishes between piddly parties rather than gargantuan wars between superpowers that suck in the entirety of humankind.

tl;dr: Small tribes agglomerated after warfare, reducing internal warfare but continuing external warfare, with the result of having fewer, but larger, more devastating wars over the millennia

Now let us turn our back on the Middle Ages, and see what happened when the small-state world with its ever-feuding parts and operetta wars gave way to our modern large-power system. The reason and apology with which it introduced itself to historians was the pacification of large regions previously torn by tribal warfare. In this it unquestionably succeeded and, because most of us grunt with delight whenever we hear the word peace, it is applauded on this account to this very day. But was the result of this regional pacification peace? Hardly. For as soon as the new nation states had established themselves on firm ground and pacified their new dominions into reliable and well co-ordinated units, their natural aggressiveness began to assert itself in exactly the same manner as was the case with their smaller predecessors whom they had wiped out because of their peace-disturbing quarrelsomeness. Once their acquisitions were properly digested, they looked again beyond their boundaries for outlets of their energies-and a new cycle of wars began, wars, however, that were qualitatively different from the earlier ones.

[...]

They occurred at longer intervals than the medieval wars. This is why we are often deluded into thinking that the pacification of large regions and their organization as great powers was beneficial to mankind after all. Even if wars were not completely eliminated, their number was greatly reduced. But it is not the quantity that matters. It is the quality that counts.

— breakdown-of-nationsp. 65

~ forest management & fire suppression practices. Small, controlled burns can be beneficial in clearing out dead wood while doing little harm to living tress, and allowing for forests to regenerate. Suppressing fires absolutely (e.g. to protect property at all costs) has the potential of letting fuel build up over time, increasing the risks of megafires that kill even the living trees and lay waste to the entire forest in the end.