During World War II, Rosenberg worked as a civilian inspector for the Army Signal Corps but was dismissed in early 1945 when his past Communist Party membership surfaced. In 1943 he had the first of some fifty meetings with Alexander Feklisov, a Soviet intelligence officer, and began providing classified military information to him, including secrets related to the manufacture of the atomic bomb. Beginning in 1946 Rosenberg started a small and ultimately unsuccessful engineering workshop with his brother-in-law, David Greenglass, who had previously worked as a machinist on the Manhattan Project.
On 17 June 1950 the Federal Bureau of Investigation (FBI) arrested Rosenberg after a series of confessions by Klaus Fuchs, Harry Gold, and David Greenglass, who turned witness for the prosecution. On 11 August Ethel Rosenberg was also arrested. The Rosenbergs' controversial trial began on 6 March 1951, deeply dividing a nation already polarized by McCarthyism and the Korean War. To some, the Rosenbergs personified the threat of atomic espionage; to others, they were unjust victims of McCarthyism and anti-Semitism. The Rosenbergs were convicted of conspiracy to commit espionage in wartime on 29 March 1951 and were sentenced to death six days later. Although it now appears that Julius—but not Ethel—was in some respects guilty of espionage, the verdict appeared shaky in 1951.
The Rosenbergs remained on death row for twenty-six months while their lawyers filed appeals and as international outrage with the verdict intensified. Both denied being communists and maintained their innocence. After President Dwight Eisenhower refused clemency, Julius and Ethel Rosenberg were put to death by electrocution on 19 June 1953, the only two civilians executed for espionage during the Cold War.
Feklisov, Alexander, and Sergei Kostin. The Man behind the Rosenbergs. New York: Enigma Books, 2001.; Radosh, Ronald, and Joyce Milton. The Rosenberg File: A Search for the Truth. New York: Holt, Rinehart and Winston, 1983.