While at King's College London, Slotin distinguished himself as an amateur boxer by winning the college's amateur bantamweight boxing championship. Later, he gave the impression that he had fought for the Spanish Republic and trained to fly a fighter with the Royal Air Force. Author Robert Jungk recounted in his book Brighter than a Thousand Suns: A Personal History of the Atomic Scientists, the first published account of the Manhattan Project, that Slotin "had volunteered for service in the Spanish Civil War, more for the sake of the thrill of it than on political grounds. He had often been in extreme danger as an anti-aircraft gunner." During an interview years later, Sam stated that his brother had gone "on a walking tour in Spain" and he "did not take part in the war" as previously thought.