June 7, 1949

June 7, 1949, marked J. Robert Oppenheimer’s appearance before the House Committee on Un-American Activities during its investigation of alleged atomic espionage. He emerged from the closed session apparently unscathed, but his testimony about former student Bernard Peters soon became public and exposed the risks of speaking candidly in a proceeding assumed to be private.

Setting and Stakes

Oppenheimer had been subpoenaed to testify and knew that one committee member, Illinois congressman Harold Velde, had worked for the FBI and investigated Berkeley’s Radiation Laboratory during the war. He appeared on June 7 before six congressmen in an executive session. Although he was there ostensibly as chairman of the Atomic Energy Commission’s General Advisory Committee, the committee was interested in alleged atomic spies, not nuclear policy.

Apprehensive but unwilling to look defensive, Oppenheimer chose not to bring a personal lawyer. He brought Joseph Volpe, the Atomic Energy Commission’s general counsel, and introduced him in that official capacity. The testimony lasted two hours. Oppenheimer was cooperative and forthcoming, a manner that would matter when his remarks later circulated beyond the closed room.

Questions About Berkeley and Former Students

The committee’s counsel began by asking whether Oppenheimer knew that a Communist cell existed among scientists at the Radiation Laboratory. He denied knowing of one. Asked about former students, he said he had not known before the war that Joseph Weinberg was a Communist and described Weinberg’s expressed views after the war as not following the Communist line.

The questioning then turned to Peters. The counsel asked whether Oppenheimer had told Manhattan Project security officers that Peters was dangerous and quite red. Oppenheimer acknowledged that he had made that assessment to his Los Alamos security officer, Peer de Silva. He explained that Peters had belonged to the German Communist Party and fought street battles against the Nazis, had been sent to a concentration camp and escaped, and, after reaching California, had denounced the American Communist Party as insufficiently committed to overthrowing the government by force. Oppenheimer added that Peters himself had told him of his German party membership.

The account was not simply a report of Peters’s political associations. Oppenheimer also repeated allegations about what Peters had said regarding armed revolution, while seeming to regard the executive session as a setting in which such disclosures would remain contained. The testimony thus joined security inquiry to a former teacher’s candid—and potentially damaging—characterization of a former student.

The Closed Session Becomes Public

The counsel withdrew the question about Peters. Before the session ended, Richard Nixon said he was impressed by Oppenheimer and pleased with his position in the atomic program. Volpe was astonished by Oppenheimer’s cool performance; the six legislators came down to shake the famous scientist’s hand. Oppenheimer appeared to leave with his standing intact, and the reception may have reinforced his belief that his public prominence offered protection.

The next day, Peters appeared before the committee for about twenty minutes. He denied having been a Communist in Germany or the United States and denied that his wife, Hannah Peters, had belonged to the party or that he knew Steve Nelson. Concerned about what Oppenheimer had said, Peters stopped in Princeton on his way back to Rochester to speak with his former mentor. Oppenheimer reassured him that the questioning had not led him to say anything derogatory.

A week later, Oppenheimer’s closed-session testimony was leaked to the Rochester Times-Union. Its headline highlighted his description of Peters as quite red. The story revived details from Peters’s past, including his escape from Dachau and the claim that he had criticized the American Communist Party for not embracing armed revolution. What had been spoken in executive session was now a newspaper account available to Peters’s colleagues and the public.

Consequences and Significance

Peters understood that the leak could put his job at risk, especially after an earlier newspaper report had already prompted him to sue for libel. He publicly denied ever having told Oppenheimer that he was a Communist. He said he had admired the fight against the Nazis and those who died at Dachau, while acknowledging that his views were unorthodox: he opposed racial discrimination and considered socialism desirable, but said he was not a Communist.

Oppenheimer emerged from the hearing without immediate damage to his own position; Peters had to answer publicly for statements attributed to him by his former mentor. The contrast gives the date its lasting significance in the account: a prominent adviser’s confidence in the apparent privacy of a congressional session coexisted with the vulnerability of a former student whose political history could be recast by a leak. The hearing’s reassuring conclusion for Oppenheimer did not protect Peters from the consequences of what had been said about him.