Freeman Dyson “often wondered how it happened that Oppenheimer changed his character so suddenly, from the left-wing bohemian intellectual at Berkely to the good soldier at Los Alamos.”
Much of it, he concluded, was due to the indirect influence of Kitty Oppenheimer’s first husband, Joe Dallet. She retained a deep and open loyalty to him and Dallet’s story was certainly striking.
Dallet was unlike the majority of the left-wing intellectuals who flocked to Spain to fight for the republic. Dallet took soldiering seriously. He believed in discipline. He quickly became an expert on the repair, maintenance, and use of machine guns. He drilled his troops with old-fashioned thoroughness, making sure that they knew how to take care of their weapons and how to use them effectively. In an anarchic situation, his unit was conspicuously well organized. His men caught from him the habit of competence, the pride of a steelworker who knew how to handle machinery. At moments of relaxation, he talked mostly about his beloved machine guns. This was the image of Joe that Joe’s friends brought to Kitty in Paris when they came to see her after his death. This was the image that Kitty brought to Oppenheimer when she married him.
From Spain to Los Alamos was a short step. Oppenheimer was as proud of his bombs as Joe Dallet had been proud of his guns. Oppenheimer became the good soldier that Kitty loved and admired. Through the Los Alamos years and for twenty years afterward, the spirit of Joe Dallet lived on in Robert Oppenheimer.
For all the suspicions that swirled around Oppenheimer in the post-war years he had been, according to Dyson, “astonishingly effective as leader of the Los Alamos project”, always devoted to America and “above all a good soldier.”
I have a vivid memory of the ice-cold February day in 1967 when we held a memorial service for Oppenheimer at Princeton. Because of the extreme cold, attendance at the service was sparse. But General Groves, old and frail, came all the way from his home to pay his respects to his friend.
There’s much more here.