In the summer of 1966, after extensive study and planning, I wrote to a number of people around the world, inviting them to join an International War Crimes Tribunal. The response heartened me, and soon I had received about eighteen acceptances. I was especially pleased to be joined by Jean-Paul Sartre, for despite our differences on philosophical questions I much admired his courage.
Source: The Autobiography of Bertrand Russell, v.3 chap. 4
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