Every country is trying one up each other.
Capitalism vs Communism Late stage Capitalism vs ??? Democracy vs Authoritarianism Socialism vs ???
Disclaimer: I don't support War or any country.
World War I was brutal
World War II was advance warfare in its initial stage. Kudos to Germany for making so much advancements even after losing the first war and having to pay reparations (Treaty of Versailles) and still able to motivate their people to fight back and challenge the innovation.
It made few countries relinquish their state controlled in third world countries and signing lot of peace treaties and formation of NATO, nuclear war treaties. Humans are really good at adapting.
Cold war is always nice to study from the technological advancements and how innovation was in a fast track after the world war II. Space era and East Germany vs West Germany. How music also influenced lot of things.