The US has major geographical and natural resource advantages that make it a superpower. We fared well after WW2 for a number of reasons, not just because we lost no infrastructure and relatively few soldiers.

Look at Japan, Germany, the UK, and France now. They were devastated (both infrastructure and population-wise) and now they are among the strongest economies in the world, coming in behind the US and China at numbers 3,4,5,6 respectively in terms of nominal GDP.

Just as forest fires burn down old trees and put nutrients back into the soil to spur new growth, so does war force countries to rebuild and rethink.

I'm not advocating for war, but it's a much more defensible thesis in my opinion (large temporary increase in aggregate demand, large permanent decrease in labor supply), much more so than increased vacation time.

Modern countries today have fertility rate around 1,4-1,9 (children per woman during all her life). USA has it aroud 1,7 for white people, I believe.

There would not be any new people. They're barely replenished with all the set of tricks you can pull.

Any soldier who falls in battle means, since wives need husbands and since it's customary to let youth fight, your nation is smaller by two. Permanently. That's what we have today, anyway.

I'm not sure what you are arguing? There's an entire generation of people (baby boomers) who were born post WW2 in a period of extremely high birth rates due to favorable economic conditions created by the war - minimal unemployment, economic expansion due to government spending, and increased spending on housing and education due to the GI Bill.

https://en.wikipedia.org/wiki/Post%E2%80%93World_War_II_baby...

That's ancient history by demographic standards. Modern wars don't create baby booms. People en masse don't want more than 2 children. Dead people want nothing.

Also, during extended period of peace, people's expectation of life increases, decent houses, good food, entertainment, self-fulfillment, etc etc.

Send them all to war, half of them will come back happy to be alive.

If you're a merciless dictator, that's definitely the easiest way to make your people happy.

War didn't enable them to rebuild, except that the US decided for geostrategic reasons to pour vast fortunes into rebuilding those countries, both allies and former enemies. That is a fairly atypical end-of-war condition.

> now they are among the strongest economies in the world

Yes, now. After decades of depression.