Julius and Ethel Rosenberg bear the dubious distinction of being the first American civilians to be executed for espionage. The pair were electrocuted on 19 June, 1953 for their roles in passing classified information regarding the atomic bomb to the Soviet Union. The Rosenbergs are often used to illustrate the paranoid anti-Communist climate of the Cold War, with some historians maintaining that the pair were innocent.
Both were born into Jewish families, and they joined the Communist party at relatively young ages. During the Second World War, Julius Rosenberg initially worked for the signal corps, but he was dismissed when his links to the Communist party were revealed. He went to work for Ethel's brother, David Greenglass. Greenglass had worked at Los Alamos, and it was later alleged that Julius used Greenglass to gather information which he then passed on to the Soviet Union.
When the Soviet Union produced a nuclear weapon shortly after the close of the Second World War, the United States was deeply suspicious. Investigation revealed a complex web of spies who most certainly passed information to the Russians, either because they sympathized with them or because they felt that the United States should not have sole control of atomic weapons. Greenglass was implicated in this web, and he in turn passed on the name of Julius Rosenberg.
The Federal Bureau of Investigation (FBI) arrested both Rosenbergs, in the hopes of forcing Julius to confess to save his wife. Both, however, pled the Fifth Amendment during their trials, and they were ultimately convicted. The Rosenberg trials have been criticized in hindsight because many people felt that they were not fairly administered, due to the Communist and Jewish affiliations of the accused. During the trials, the guilt of the pair was more or less assumed, and it was not until after the trial that international outcry brought attention to the issue.
Despite two years of campaigning, the death sentence was upheld for the pair. Later evidence has suggested that Julius, at least, was most certainly involved in espionage, although the value of the information is disputed. Much of this information came from the Venona Project, a cooperative agreement between the United States and Great Britain to intercept and decode Soviet communications. Numerous documents on the Rosenberg case have been made available by the Central Intelligence Agency and FBI, since there has been so much public interest in the case.