Rosenberg Trial (1951): Julius and Ethel Rosenberg Spy Case

The Rosenberg trial was the 1951 federal prosecution in New York of Julius and Ethel Rosenberg, an American couple accused of passing atomic and military secrets to the Soviet Union. Held from 6 to 29 March 1951 at the height of the early Cold War, it ended in death sentences that made the Rosenbergs the only American civilians executed for espionage during the Cold War, and it remained bitterly contested for decades.

Background: from Fuchs to Greenglass

The case grew from the confession of the British physicist Klaus Fuchs in January 1950. Fuchs’s description of his American courier led the FBI to Harry Gold, a Philadelphia chemist, who was arrested in May 1950. Gold in turn identified David Greenglass, a former Army machinist who had worked at Los Alamos on the Manhattan Project.

Greenglass confessed in June 1950 and named his brother-in-law Julius Rosenberg, an electrical engineer and former member of the Communist Party, as the man who had recruited him. Julius was arrested on 17 July 1950. His wife Ethel, Greenglass’s sister, was arrested on 11 August, in part, officials later acknowledged, to pressure Julius into co-operating.

The arrests came weeks after the outbreak of the Korean War and months after the first Soviet atomic test, in a climate of intense fear of communist subversion.

The Rosenberg network

Julius Rosenberg had been an active communist in New York since his student days at City College. During the Second World War he worked as a civilian engineer for the US Army Signal Corps, until he was dismissed in 1945 when his past party membership came to light. By then, according to later evidence, he had been working for Soviet intelligence for several years.

He recruited friends from his college and engineering circles, several of whom worked in defence industries. They passed material on radar, sonar, jet aircraft and the proximity fuse, a device that made anti-aircraft shells explode near their target. These secrets were arguably more valuable to the Soviet Union than anything the network supplied on the atomic bomb.

When the FBI began to close in, some members fled. Joel Barr and Alfred Sarant, two engineers in the network, escaped and later worked on Soviet military electronics. Morton Sobell fled to Mexico in June 1950, but was seized there and handed over to US authorities in August.

The trial

The trial opened on 6 March 1951 before Judge Irving R. Kaufman. The prosecution was led by US Attorney Irving Saypol, assisted by the young Roy Cohn; the Rosenbergs were defended by Emanuel Bloch. A third defendant, Morton Sobell, an engineer and college friend of Julius, was tried with them.

David Greenglass testified that Julius had recruited him in 1944–45 and that he had given Julius and Harry Gold sketches and descriptions of the high-explosive lens molds used in the implosion bomb. Ruth Greenglass testified that Ethel had typed up her brother’s handwritten notes in the Rosenbergs’ apartment, the most damaging evidence against Ethel. Harry Gold described collecting material from Greenglass in Albuquerque in June 1945, using a torn Jell-O box panel as a recognition signal.

Both Rosenbergs denied the charges and invoked the Fifth Amendment when asked about Communist Party membership. On 29 March 1951 the jury found all three defendants guilty of conspiracy to commit espionage.

Sentences and appeals

On 5 April 1951 Judge Kaufman sentenced Julius and Ethel Rosenberg to death, declaring their crime “worse than murder” and blaming them for the communist aggression in Korea. Sobell received 30 years. In a separate proceeding Greenglass, who had pleaded guilty, received 15 years; Gold had already been sentenced to 30 years.

Over the next two years appeals failed. The case became an international cause, with demonstrations in Europe and appeals for clemency from figures including Pope Pius XII, Albert Einstein and Jean-Paul Sartre. Supporters argued that the sentences were excessive and that the trial reflected anti-communist and antisemitic prejudice; the Rosenbergs, Kaufman, Saypol and Cohn were all Jewish. On 17 June 1953 Justice William O. Douglas granted a stay of execution, but the full Supreme Court vacated it two days later. President Dwight D. Eisenhower refused clemency, and the Rosenbergs were executed at Sing Sing prison on 19 June 1953.

The debate over the sentence

The death sentences were exceptional. Fuchs, who passed far more important atomic information, received 14 years in Britain, the maximum available there. Critics argued that the Rosenbergs were being punished for refusing to confess and name others, and some later evidence suggests that officials hoped the threat of execution would make Julius talk.

Prosecutors and Judge Kaufman presented the case as one of the gravest betrayals in American history, coming at a time when American soldiers were fighting communist forces in Korea. Defenders of the verdict pointed out that the Rosenbergs had been convicted by a jury and that their appeals were heard by the courts, including several petitions to the Supreme Court.

Key people

Julius Rosenberg (1918–1953) recruited and managed a group of engineers who passed military technology to Soviet intelligence. Ethel Rosenberg (1915–1953), a former secretary and aspiring singer, maintained her innocence to the end. David Greenglass served nine and a half years and later lived under an assumed name. Morton Sobell was released in 1969 and in 2008 publicly admitted that he and Julius had spied for the Soviet Union.

Later evidence

In 1995 the US government released the Venona decrypts, wartime Soviet cables broken by American codebreakers. They identify Julius Rosenberg, under the code names ANTENNA and later LIBERAL, as an active Soviet agent who ran a productive network passing radar, jet engine and other military technology. They refer to Ethel as aware of her husband’s work but do not give her a code name.

In 2001 Greenglass told the journalist Sam Roberts that he had testified about Ethel’s typing without a real memory of it, to protect his wife. His grand jury testimony, unsealed in 2015, did not mention it. Released Soviet-era sources and the memoirs of the former KGB officer Alexander Feklisov, who had handled Julius in New York during the war, also confirmed Julius’s work for Soviet intelligence while describing Ethel as a supporter rather than an active agent. Scholars also note that the atomic material Greenglass supplied was crude compared with what Fuchs and the Los Alamos physicist Theodore Hall provided.

Myths and facts

• Myth: the Rosenbergs were entirely innocent victims. Venona and Sobell’s admission show that Julius was a Soviet agent.
• Myth: the Rosenbergs gave the Soviets the atomic bomb. Their network’s atomic contribution was secondary; Fuchs’s information was far more significant.
• Fact: Ethel’s conviction rested heavily on testimony her brother later admitted was unreliable, which is why her case remains especially controversial.

Timeline

• 1950, 2 February: Klaus Fuchs is arrested in Britain.
• 1950, 23 May: Harry Gold is arrested.
• 1950, 17 July: Julius Rosenberg is arrested.
• 1950, 11 August: Ethel Rosenberg is arrested.
• 1951, 6 March: Trial opens in New York.
• 1951, 29 March: Guilty verdicts.
• 1951, 5 April: Death sentences imposed.
• 1953, 19 June: The Rosenbergs are executed at Sing Sing.
• 1995, July: First Venona decrypts are released.

Why it matters

The Rosenberg case became a symbol of the Second Red Scare, dividing Americans for half a century. It shows both the reality of Soviet espionage in the United States and the dangers of a justice system operating under political pressure.