Comment by safety1st

This stuff about the world being peaceful due to the industrial revolution doesn't make a lot of sense to me. For one thing, the IR significantly predated WW1 and WW2. It didn't prevent those, so how'd it cause the "long peace" afterwards? The predominant theory about this in international relations is hegemonic stability theory - https://en.wikipedia.org/wiki/Hegemonic_stability_theory - there have been several periods throughout history that were relatively peaceful because an exceptionally strong nation state decided to step up and enforce a peace. Considering that the US was half of global GDP at the end of WW2 and has long been more than happy to sanction anyone who conducts in an (unapproved) war (such as Russia right now), the modern era of "long peace" fits this theory pretty well.