Michael Sidorovich: Spain, Spies, and Soviet Ties

Michael Sidorovich’s story provides a glimpse into the communist affiliations of some International Brigades volunteers. Years after his return from Spain, Sidorovich became entangled in the Rosenberg case.

Birth of a Young Communist

Russian Archive of Socio-Political History (RGASPI)

Michael Sidorovich was born in 1916 in New York City. His parents, Alexander and Sophie, were Jewish immigrants from Russia. Michael joined the Young Communist League in 1934 when he was 18 while attending Stuyvesant High School in New York. During this time, he befriended Julius Rosenberg, a fellow student who was a leader in the League and later became a prominent spy for the Soviet Union. After high school, Sidorovich enrolled at the Polytechnic Institute of Brooklyn to continue his education in engineering. He remained involved with the Communist Party throughout college.

Shipping off to Spain

According to his application to join the Spanish Communist Party in 1938, Sidorovich, also known as “Mike Cedar,” was politically active before he left for Spain. He had joined a union affiliated with the Committee for Industrial Organization (CIO) and had participated in various labor strikes and demonstrations. His membership in the New York branch of the Young Communist League also motivated him to fight fascism in Spain.

In October 1937, at 21, Sidorovich put his political beliefs into practice and traveled to Spain with other volunteers to join the Abraham Lincoln Brigade to fight against Franco. He arrived in November after a dangerous crossing of the Pyrenees mountains along the French-Spanish border. Sidorovich first served as cartographer in a division in the southern region of Andalucía and later in the 35^th Artillery Battery.

After months of active combat and hospitalization, Sidorovich left Spain and returned to New York City on February 4, 1939. Though the Spanish Republic had been defeated by Franco and his allies, Sidorovich’s political commitments remained strong.

Return to America and the Rosenberg Trial

Following his return from Spain, Sidorovich resumed his studies at Brooklyn Polytechnic Institute and his friendship with Julius Rosenberg. In 1939, Paul Williams, a fellow volunteer from the International Brigades, employed Rosenberg and Sidorovich at his company, Williams Aeronautical Company, to test flight equipment for the United States.

**Michael Sidorovich’s FBI file**
(FBI Records: The Vault)

While many returning volunteers were prevented from getting jobs because of their involvement in the Spanish Civil War, in 1941, Sidorovich began working as a draftsman on classified Navy contracts, a job that he maintained throughout most of World War II. In 1944, he and his wife, Anne, moved to Cleveland, Ohio. FBI records indicate that Sidorovich was registered with the American Labor Party (ALP), a socialist organization founded in the 1930s in the state of New York. The ALP was considered by the Committee of Un-American activities “a Communist front.”

The FBI investigation of Sidorovich was prompted by the case against Julius and Ethel Rosenberg, a couple accused of spying for the Soviet Union. The Rosenbergs were tried and executed in 1953. Sidorovich had been identified as a member of Rosenberg’s spy ring. He and his wife were believed to have photographed classified information and delivered the microfilms to the Soviets. In his testimony to the grand jury, Sidorovich denied all charges. He acknowledged his membership in the Young Communist League in the 1930s, but said that he was no longer involved with communism. In the end, Michael and Anne Sidorovich were not sent to trial.

**Michael and Anne Sidorovich.**
National Archives (Julius and Ethel Rosenberg Case).

Continued Surveillance

This era of staunch anti-communism in American history is known as McCarthyism, where hundreds of individuals, like Sidorovich, were targeted for suspected involvement with the Soviet Union and communist organizations. Michael and Ann Sidorovich continued to be closely monitored for several years following the Rosenberg trial, with the FBI keeping records on their jobs, social interaction, and correspondence as late as 1966. Sidorovich died of a heart attack on March 21, 1962. The FBI continued to monitor his wife’s whereabouts, suspecting that she might still be working with Soviet contacts.

**The Veterans of the Abraham Lincoln Brigade were one of the organizations targeted by the government for its links to Communism.**
New York *Daily News*, May 5, 1954

Aaron Katz, the director of the National Committee to Reopen the Rosenberg case, advocated for several decades (1963-2005) to exonerate Ethel and Julius Rosenberg. Katz’s uncle was Michael Feller, another signatory of the fan who had joined the Communist Party USA (CPUSA) and gone to Spain in 1937. Feller and Sidorovich were together in the Anti-Tank Battery 129. While Feller died in Europe during World War II and never witnessed the height of American anti-communism, his nephew Aaron Katz spent much of his life fighting for the exoneration of the Rosenbergs and for the right of political activism without fear of prosecution.

Many details of Sidorovich’s time in Spain remain unknown, but his life after the Spanish Civil War sheds light on the political climate in the United States during the 1950s. Despite the Soviet Union and the United States being allies during World War II against Nazi Germany, which had supported General Franco in Spain in the 1930s, many Americans remained suspicious of the international volunteers who fought in Spain against the rise of fascism.

Sidorovich Profile