The Rosenberg Case: A Trial and Conviction of Espionage

Julius and Ethel Rosenberg were the first Americans sentenced to death under the conviction of conspiracy to commit espionage during peacetime for trading atomic bomb secrets with the Soviet Union.

Feb 17, 2023By Amy Hayes, BA History w/ English minor
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Julius and Ethel Rosenberg separated after being convicted of conspiracy to commit espionage by Roger Higgins, 1951, via Library of Congress, Washington DC


The Julius and Ethel Rosenberg trial and conviction was a Soviet espionage case that ended with controversies among the public. Julius and Ethel were convicted of conspiracy to commit espionage in relation to trading US government secrets to the Soviet Union, most notably documents pertaining to the Manhattan Project. The Rosenbergs were put on trial around the same time the second Red Scare began. Communism and Soviet spies infiltrating the US government were becoming serious concerns. Julius and Ethel managed to maintain their innocence throughout the trial, but they were ultimately sentenced to death based on very limited evidence and questionable testimony of others involved.


Julius & Ethel Rosenberg Meet Through Communist Party Associations

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Photograph of young Ethel and Julius Rosenberg courtesy of Howard Gotlieb Archival Research Center, via Boston University


Julius and Ethel Rosenberg were both born in New York City and had similar interests. Ethel was born Ethel Greenglass in Manhattan to a Jewish family on September 28, 1915. Julius was born to a family of Jewish immigrants on May 12, 1918. Julius and Ethel joined the Young Communist League (YCL) shortly after finishing high school. Their reasons for associating with the group aren’t clear, but Ethel was involved in labor disputes and organizing union strikes prior to joining the YCL.


Through their membership with the YCL, Julius and Ethel met in 1936. They married three years later. Ethel was employed by the National New York Packing and Shipping Company as a secretary after graduating high school in 1931. Julius attended the City College of New York, where he received a degree in electrical engineering. After he graduated, Julius joined the US Army Signal Corps in 1940 as a civilian engineer and later became an inspector.


Early Espionage Activities of Julius Rosenberg

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Main gate entrance to the atomic bomb project site at Los Alamos National Laboratory, via Atomic Heritage Foundation


While working in the Signal Corps, Julius began participating in espionage activities. He provided numerous classified documents to his Soviet handler, Alexander Feklisov, including a design model for a proximity fuze. Julius left the Communist Party of the USA (CPUSA) in 1942 to prevent any potential suspicions about his involvement. Due to the tensions between the US and the Soviet Union following World War II, a period known as the Cold War, any associations with the Communist Party raised red flags for individuals employed by the US government.

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Despite cutting ties with the Communist Party, Julius was fired from his position with the Signal Corps in 1945 when they learned about his previous involvement. Through declassified documents that were released years after the Rosenberg trial, it was made aware that Julius was a leader of a Soviet spy ring. Julius stole information and also recruited other individuals to trade secrets about various projects the US government was working on.


Julius worked at the Emerson Radio Corporation for a year after his termination from the Signal Corps. In 1946, he joined together with Ethel’s brother, David Greenglass, to start up the G&R Engineering Company. David Greenglass was one of Julius’ recruits for Soviet espionage. Greenglass started working on the Manhattan Project in the summer of 1944 under the Special Engineer Detachment of the US Army. As a skilled machinist, Greenglass was transferred to the Los Alamos National Laboratory in August 1944. Los Alamos was the Manhattan Project research site in New Mexico where the atomic bomb was constructed. Greenglass stole secrets about the construction of the atomic bomb while at Los Alamos and delivered them to Julius.


The Rosenberg Spy Ring Crumbles

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Mugshots of those who were arrested for Soviet espionage activities with connections to Julius – from top left to bottom right: Julius Rosenberg, Ethel Rosenberg, Klaus Fuchs, David Greenglass, and Ruth Greenglass, collage created by author, via Atomic Heritage Foundation


One of Greenglass’ fellow colleagues at Los Alamos, Klaus Fuchs, was a German physicist who also gathered atomic bomb secrets and shared them with the USSR. The US Army Signal Intelligence Service (SIS) found out that Fuchs was a Soviet spy trading secrets on the Manhattan Project in 1949. Shortly after learning this information, Fuchs was arrested in early 1950. This launched an investigation into the spy ring that Fuchs was a part of, which also included David Greenglass and lab chemist Harry Gold. During the investigation and questioning, Greenglass revealed Julius and Ethel’s involvement in their espionage activities.


The FBI arrested Julius and Ethel Rosenberg in July and August 1950 based upon Greenglass’ accusations of their involvement. In August 1950, Greenglass testified before a secret grand jury and admitted to committing espionage and giving secrets of the Manhattan Project to Julius to pass to his Soviet handler. During this initial testimony, Greenglass never named his sister Ethel as being a part of the spy ring. However, he changed his testimony just two weeks prior to the start of the Rosenberg trial in February 1951. Julius and Ethel Rosenberg were charged with conspiracy to commit espionage. Since it was a conspiracy charge, tangible evidence wasn’t required for the Rosenbergs to be convicted.


Julius and Ethel Rosenberg Go on Trial

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Standing mugshots of Julius and Ethel Rosenberg taken upon their arrests in 1950, collage created by author, via National Archives Catalog


Julius and Ethel Rosenberg were both tried under the charges of conspiracy to commit espionage. The charges were based upon violations of the Espionage Act of 1917. The Espionage Act made it illegal to obtain information, photographs, or copies of descriptions of information with the intent or reason of using such information or materials in a way that threatens national security or helps the advances of a foreign country.


The Rosenberg trial began on March 6, 1951 at the Southern District federal court of New York. It lasted for about three weeks. The trial received a great amount of media attention, which later resulted in disagreements on the outcome. Ethel’s involvement in the case was minimal. There was no hard evidence that suggested she was involved in committing espionage with Julius. In order to get a plea deal, however, David Greenglass accused Ethel of typing the atomic bomb notes that he gave to Julius. Greenglass’ wife, Ruth, was not convicted on any charges. It was later revealed that David twisted his testimony to prevent Ruth from being indicted.


Julius and Ethel maintained their innocence throughout the trial by asserting their Fifth Amendment rights and refusing to answer questions. This was a tactic to prevent incrimination upon themselves. Refusal to answer questions about their involvement with the Communist Party during a period of heightened espionage paranoia caused many to quickly label them as spies based on the popular belief that all Communist members were Soviet spies.


Conviction & Sentencing of the Rosenbergs

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Headline for the Rosenbergs receiving the death sentence by electric chair by San Antonio Express, 1953, via San Antonio Express-News


Julius and Ethel were found guilty of conspiracy to commit espionage on March 29, 1951. Judge Irving Robert Kaufman sentenced them to death by electric chair on April 5, 1951. Julius and Ethel became the first Americans to be sentenced to death on the conviction of espionage during peacetime.


Judge Kaufman made a statement to the Rosenbergs justifying his decision by stating:


I consider your crimes worse than murder… I believe your conduct in putting into the hands of the Russians the A-bomb years before our best scientists predicted Russia would perfect the bomb has already caused, in my opinion, the Communist aggression in Korea, with the resultant casualties exceeding 50,000 and who knows but that millions more of innocent people may pay the price of your treason.”


The decision was applauded by many but also came as a shock to those who believed the Rosenbergs were innocent. The lack of evidence against the Rosenbergs made the case highly controversial. David Greenglass served as the primary witness for the Rosenbergs’ involvement in committing espionage, and their fate mainly relied on his testimony. As a result of Greenglass’ plea deal, he was sentenced to 15 years in prison for committing espionage. He was released in 1960 after serving almost ten years.


Another co-conspirator, Morton Sobell, who was tried alongside the Rosenbergs, was sentenced to 30 years in prison and released after serving almost 18 years. Julius and Ethel’s death sentence was much harsher than all other individuals involved in the Rosenberg case. It’s likely that their harsh sentencing was due to their lack of cooperation within the court and refusal to answer numerous questions.


Declassified Documents Reveal the Truth about Julius & Ethel Rosenberg


The US Army Signal Intelligence Service launched a secret counterintelligence program codenamed VENONA in 1943 to examine and potentially decrypt Soviet communications. The program was initiated by Deputy Chief of Military Intelligence Carter W. Clarke.


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Julius Rosenberg handcuffed on his way to the courthouse to hear the jury’s verdict courtesy of Mary and Dan Soloman, via National Gallery of Art, Washington DC


Almost 3,000 messages were obtained and decrypted, most of which were throughout World War II. Part of the decryption process was determining the identities of secret codenames used in encrypted cables.


The National Security Agency terminated the VENONA project in 1980. The first series of VENONA documents were declassified in July 1995 and revealed a number of translations that related to Soviet espionage activities and the atomic bomb. Other translations included KGB communications with the Moscow Center. After the release of the documents, it became clear that Julius Rosenberg was heavily involved in trading US government secrets and acted as a leader of a Soviet spy ring under the codenames Antenna and Liberal.


The documents also revealed that Ruth Greenglass was involved in espionage activities with David Greenglass, and Ethel Rosenberg was never mentioned in any of the obtained and decrypted messages. In 2008, private transcripts of almost all the witnesses who testified before a secret grand jury were made public. The transcripts didn’t reveal David Greenglass’ original testimony made before the grand jury, which was released upon his death in 2015. His original testimony contradicted the testimony he gave to the jury in the Rosenberg trial.


The original testimony would’ve proved that Ethel played a very minor role in espionage activities if any at all. It also would’ve implicated Ruth Greenglass, but David decided to change his testimony to protect his wife over his sister. The testimonies given to the secret grand jury weren’t made available to the Rosenbergs’ lawyers for the trial. A campaign was launched by the Rosenberg Fund for Children in 2016 to petition for the exoneration of Ethel Rosenberg following the release of the grand jury materials. Despite the petition receiving thousands of signatures and media coverage, Ethel wasn’t exonerated.

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By Amy HayesBA History w/ English minorAmy is a contributing writer with a passion for historical research and the written word. She holds a BA in history from Old Dominion University with a concentration in English. Amy grew up in the historic state of Virginia and quickly became fascinated by the intricate details of how people, places, and things came to be. She specializes in topics on American history, Ancient and Medieval England, law, and the environment.