What was the Chevalier incident in Oppenheimer?

Many of J Robert Oppenheimer's relationships are also explored, and one that has particular significance is that with his friend Haakon Chevalier (played by House of the Dragon star Jefferson Hall), who was at the centre of a key moment referred to as the Chevalier incident.

But what exactly was this incident, and how did it impact Oppenheimer later in his life? Read on for everything you need to know.

What was the Chevalier incident in Oppenheimer?

Haakon Chevalier and J. Robert Oppenheimer first met when they were both teaching at Berkeley in 1937 – and were involved together in leftist causes – but it was in 1942 that their relationship had its key moment.

At this time, Chevalier told his friend about a conversation he had had with the scientist George Eltenton, during which it was revealed that the Soviet Union was attempting to spy on the Manhattan Project through Eltenton.

Oppenheimer only reported that this conversation took place much later on, obscuring certain facts about it in order to protect Chevalier's identity and falsely claiming that three men at Berkeley had been solicited for nuclear secrets.

In a conversation with Leslie Groves later that year, he eventually admitted that Chevalier was the man who had contacted him, and also revealed that his brother Frank had been approached.

When inconsistencies were first spotted after he reported the incident in 1943, it briefly led to calls for Oppenheimer's dismissal from the Manhattan Project – but Groves fought his corner and declared that he was "absolutely essential to the project".

However, at the security hearing more than a decade later, a transcript of his earlier confession that he had fabricated certain details in order to protect Chevalier was put forward as evidence.

This played a crucial role in painting Oppenheimer as an untrustworthy figure and in the eventual decision to revoke his security clearance, with Kenneth D Nichols claiming in a letter outlining the charges against Oppenheimer that the incident proved he "is not reliable or trustworthy".

What happened to Haakon Chevalier?

Following the House Subcommittee on Un-American Activities hearing, Haakon Chevalier lost his job at Berkely in 1950.

Due to struggles to find employment in the US, Chevalier moved to France to take up work as a translator.

Chevalier only returned to the US in 1965 to attend his daughter's wedding in San Fransisco.

He also took part in the 1981 Oscar-nominated documentary The Day After Trinity, which tackled Oppenheimer's life and the creation of the atomic bomb.

Chevalier died in 1985 at the age of 83 in Paris, France.

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