What about Dadaism? The meaninglessness/war/violence of the modern world is their thang. So, Dada=Post Modernism? Or is there more to one or the other to screw me up?
Dadaism is tricky. It's meant to be tricky, I guess. In retrospect it does look more like a precursor to post-modernism. At the time, it was considered the far edge of Modernism.
In a way, Dadaism is like the kid who doesn't show his work in math class. It immediately seizes the implications of Modernism's formal concerns and jumps ahead to say, "Hey, what's so pure about these forms anyway? Why presume these are absolute values? If all bets are off and we're making up new rules from scratch, let's question all the assumptions."
And, as you note, Dadaism was a reaction to the carnage of modern war. It basically wants to challenge the entire dominant cultural model. To explode forms entirely, to break from all previous models of meaning. Because the "meanings" all added up to an insane kind of culture.
So that's some of the same political edge in post-modernism as well: all this adds up to humans being exploited and ground up.
A lot of Dadaists saw a kind of validation when they saw their first tanks painted in camouflage. To their mind, this played like "Cubism Will Kill You."