In fact Wittgenstein, having served in the Austrian army in the first world war, did war work as a research chemist in the British Health Service during the Second World War, which given the hostility to foreign nationals was about the most he could have contributed to the British War Effort 'against Hitler'.
The English Hegelian philosopher RG Collingwood in his autobiography concluded that the analytic philosophy of which Wittgenstein was a proponent, prepared the ground intellectually for Fascism, because it turned away from the bigger questions into pedantry and sophistry. But on the other hand there have been no shortage of philosophers working in England who took the opposite view, seeing German militarism as the outcome of Hegel's German Idealism. In arguning that case, Karl Popper's The Open Society and its Enemies was only treading ground well-worn by LT Hobhouse. But Hobhouse was talking about Bismark, not Hitler.
-- Jim heartfield