Here is how the USSR’s elaborate atomic spy system worked. Try to follow: Emil Julius Klaus Fuchs was a British nuclear scientist and a Russian spy, working with an American contact he did not know. That contact turned out to be Harry Gold, a chemist, who was in contact with an enlisted man assigned to Los Alamos. The enlisted man, David Greenglass, would pick up packages and deliver to Gold. Giving him the instructions was a shadowy figure named “John,” a Soviet former diploma, who turned out to have left New York in 1946, meaning there had to be another one giving orders. Further interrogation uncovered the real culprit: Ethel Rosenberg, Greenglass’s sister, and her husband Julius.

On this day, March 29, in 1951 Julius and Ethel Rosenberg were both sentenced to death for their role is passing on nuclear secrets to the USSR.

The Soviet Union created a national issue after the conviction of the couple, protesting the “legalized murder” and the “travesty of justice” carried out in the courts. Despite a few words early on about a “frame-up,” most of their effort went into protesting the punishment rather than denying the crime. American communist sympathizers did all they could as well, filing court challenges and picketing outside, successfully dragging on the case for several years.