Query: What did Wittgenstein and Hayek do during the first world war?
Context: Although Hayek met Wittgenstein on only a few occasions, Hayek said that Wittgenstein's philosophy and methods of analysis had a profound influence on his own life and thought. In his later years, Hayek recalled a discussion of philosophy with Wittgenstein, when both were officers during World War I. After Wittgenstein's death, Hayek had intended to write a biography of Wittgenstein and worked on collecting family materials; and he later assisted biographers of Wittgenstein.