Who were the first American civilians executed under Section 2 of the Espionage Act?

Julius and Ethel Rosenberg were American citizens tried for, convicted, and executed for conspiracy to commit espionage. They were instrumental in the passing of information about the atomic bomb to the Soviet Union under Joseph Stalin, speeding his development of Soviet nuclear weapon development.

In 1995, the United States government released a series of decoded Soviet cables, codenamed VENONA, which confirmed that Julius acted as a courier and recruiter for the Soviets, but did not provide definitive evidence for Ethel's involvement.Ethel's brother David Greenglass, whose testimony had condemned her, later stated that he had lied to protect his own wife Ruth, who had been the actual typist of the classified documents he stole, and that he was encouraged by the prosecution to do so. Morton Sobell, who was tried with the Rosenbergs, admitted he was a spy and stated that Julius Rosenberg had spied for the Soviets, and that Ethel Rosenberg, "knew what he was doing.”