Nihilism has nothing to do with either world war. You’re likely trying to blame Nietzsche, who was the polar opposite of a nihilist, for German nationalism. The radical optimist Nietzsche, in his old age while writing Ecco homo, disavowed his German heritage and spoke about how awesome Poland and his polish identity were.

Nihilism is only just now having an impact in the academy as it is the intellectual foundation of post modernist and critical theory.