The Baseball Player-Turned-Spy Who Went Undercover to Assassinate the Nazis’ Top Nuclear Scientist

On December 18, 1944, a 42-year-old man masquerading as a Swiss physics student settled his 6-foot-1 frame into a chair in a Zurich lecture hall. Instead of simply listening to the brilliant insights offered by the physicist at the podium, the man was trying to understand enough of the scientist’s native German to identify key words—words that could change, or perhaps even destroy, the world. All the while, he was hoping the gun tucked into his jacket pocket wouldn’t fall out, as it had during his trip across the Atlantic.

The audience member was no ordinary student. In fact, he wasn’t a student at all. He was a retired baseball player named Morris “Moe” Berg, and the American government wanted him to assassinate a man dubbed “the most dangerous possible German in the field” of physics: Werner Heisenberg, director of the Nazi nuclear program.

An average-at-best catcher who played well past his prime, Berg joined the Office of Strategic Services (OSS), a precursor to the CIA, in 1943. Nicknamed the “brainiest man in baseball” due to his knack for languages and quick wit, he found himself behind enemy lines five years after he hung up his cleats for the last time. A polymath who loved the press but was reluctant to discuss his personal life, he was a man of contradictions who crossed paths with many of the leading figures of the day, from Babe Ruth to Franklin D. Roosevelt to J. Robert Oppenheimer.

Moe Berg, baseball catcher

Born on March 2, 1902, in Harlem, New York, Berg was the youngest child of Bernard Berg, a Jewish Ukrainian immigrant, and his wife, Rose Berg. A self-made pharmacist with his own shop, Bernard, who moved his family to Newark, New Jersey, in 1906, was a firm believer in the American dream. He expected all three of his children to take full advantage of educational opportunities and pursue respectable careers. Two heeded their father’s wishes, becoming a doctor and a teacher. But baseball and espionage weren’t on Bernard’s list of preapproved professions, and he refused to attend any of his son’s games throughout his career.

Berg was the most intellectually gifted of the three siblings. A precocious youth, he asked his mother to send him to school at age 3. After graduating from high school in 1918, Berg studied modern languages at Princeton University­­, where he was one of the few Jewish students in the class of 1923. He claimed varying degrees of proficiency in at least six languages, including German, French, Japanese and Spanish, but his true passion was baseball.

“From the first, baseball made [Berg] very happy,” writes biographer Nicholas Dawidoff in The Catcher Was a Spy: The Mysterious Life of Moe Berg. “He would spend a generous share of his life inside ballparks. He felt comfortable, truly at ease, on the field or in the stands.”

Berg started playing baseball at a local Episcopal church at age 8, adopting the pseudonym Runt Wolfe to mask his Jewish heritage at a time of widespread antisemitism. He was a star on both his high school and college teams, refusing to slow down until he reached the majors in 1923. By the time he retired in 1939, he had played for five professional teams, including the Chicago White Sox and the Boston Red Sox, mostly as a backup catcher. During the off seasons, Berg earned a law degree from Columbia University, took graduate-level classes at the Sorbonne in Paris and even worked at a New York law firm.

Berg’s relationship with his family was strained, in large part due to his father’s disappointment over his career choice, but he never hurt for companionship. He cultivated cheering fans, countless friends and a press corps that hung on to his every word. Robert Elias, a historian at the University of San Francisco, says Berg “had a lot of friends in baseball … [who] ranged all the way from the people in the bullpen to people in the upper echelons.” Yet Berg, who never married or had children, was also notoriously private, refusing to discuss certain aspects of his personal life.

Despite his lackluster performance on the baseball field—his career batting average was .243, and he hit just six home runs during his 16 years in the major leagues—Berg had a larger-than-life media presence. While other players were rounding the bases or waiting for their turn in the lineup, Berg entertained from the bench, telling stories about his travels, detailing the etymology of random words and chatting with the press in whatever language struck his fancy. Nicknamed “Professor Berg” by one admiring sports writer, he was the subject of teammates’ admiration and confusion alike. One player said, “He can speak seven languages, but he can’t hit in any of them.” Another called him “the strangest man ever to play baseball.”

Moe Berg, baseball ambassador

On November 29, 1934, a group of American baseball all-stars, including Ruth, Lou Gehrig and Lefty Gomez, faced off against a Japanese team in Omiya as part of a goodwill mission organized by retired player Herb Hunter. As Elias explains, this tour and others like it aimed to use “baseball … to create better relations and forestall any real, serious conflict” with Japan, which had eagerly embraced the sport following its introduction to the country in 1872. Relations between the United States and Japan were tense at the time, exacerbated by Japan’s expansionist fervor and military incursions in China.

Berg, a last-minute addition to the lineup who had previously visited Japan as part of a 1932 tour, wasn’t with his team that November day. Instead, he was across town in a kimono, trying to sneak his film camera onto the roof of St. Luke’s Hospital. Introducing himself in Japanese, Berg claimed to be a friend of U.S. Ambassador Joseph Clark Grew and his daughter, Elsie Lyon, who was recovering from childbirth on the fifth floor. Berg never delivered the flowers he brought for the new mother, but he did capture 23 seconds of footage of the Tokyo skyline and a nearby port.

While his teammates were batting for peace, Berg was preparing for the possibility of war. Sam Kean, author of The Bastard Brigade: The True Story of the Renegade Scientists and Spies Who Sabotaged the Nazi Atomic Bomb, says Berg was “astute and aware of international relations.” Beyond the innate curiosity that defined his behavior, he was “thinking about things in the future,” and he took the footage “just in case [the U.S.] needed it.” Unbeknownst to Berg, he was also setting into motion what ranks among the strangest career changes in baseball history. The catcher from Newark was well on his way to becoming a spy.

Moe Berg, OSS spy

After the 1934 trip to Japan, Berg struggled to find a roster willing to sign a 30-something backup catcher. He joined the Boston Red Sox in 1935, averaging fewer than 30 games each season, then switched to coaching after his retirement in 1939. By the end of his baseball career, he knew the game better than most, as demonstrated in “Pitchers and Catchers,” his 1941 essay for the Atlantic. As recently as 2018, the New York Times praised this write-up as “one of the most insightful works ever penned about the game.”

On the eve of Japan’s attack on Pearl Harbor in December 1941, Berg started exploring other professions that would support his lavish lifestyle. Despite his limitations behind home plate, Berg could still catch the attention of the powerful individuals around him, just as he always had. Nelson Rockefeller, the future vice president of the U.S., and William Joseph “Wild Bill” Donovan, a high-ranking official in President Roosevelt’s administration, introduced Berg to a line of work that would allow him to explore the world, use some of the languages he knew and fight for his country, all on the government’s dime. He jumped at the opportunity, weighing his options within the intelligence community before accepting a position with Rockefeller’s Office of the Coordinator of Inter-American Affairs (OIAA) in January 1942.

Moe Berg—Third String Catcher & All-Star Spy

An @MLB player, OSS operative and legendary linguist—Berg was one of the most remarkable secret spies ever deployed by the US.

During WWII, he was sent a mission to assassinate Werner Heisenberg, the head of Nazi Germany's… pic.twitter.com/R2fwvHfY7z

— The Spy Museum (@IntlSpyMuseum) March 31, 2023

That summer, Berg screened his tape of the Tokyo skyline for American officials. The recordings held little strategic value. They were “brief, amateurish panoramas made by an adventurous person using a movie camera for the first time,” writes Dawidoff. Still, the biographer adds, Berg’s tapes demonstrated that he was “an eager, well-known man” who wanted to help the war effort, separating him from “the thirsty mob of prospective dollar-a-year men” seeking to enrich themselves on wartime government expenditures.

During his stint with the OIAA, Berg traveled across the Caribbean and South America, speaking with anyone and everyone he could, often in their native French or Spanish, and gauging the morale of the soldiers stationed abroad. He quickly realized that South America wasn’t going to be one of the major staging grounds of World War II, so he requested a transfer to where the action was: Europe.

The OSS, a nascent organization headed by Donovan—a raucous, eccentric cowboy type—was better placed to fulfill this request than the OIAA. The first independent intelligence agency in the U.S., the OSS “just did not have very tight controls on [its] people,” says Kean. “People were just doing wild things all over the world.” Berg was happy to become one of those free agents, sent to Europe to gather intel on the Nazis’ nuclear program and, when possible, compel prominent scientific minds to relocate to the U.S.

Berg worked alongside Boris Pash’s Alsos mission, an Allied initiative tasked with undermining the enemy’s scientific development. The World War I veteran and his top-secret operation were everything that Berg was not. Pash was punctual, by the book and always in uniform; Berg was erratic, informal and often seen wearing a loose tie. Pash traveled with Allied forces as they liberated occupied territories; Berg generally came in after the shooting stopped and smooth-talked scientists. As Kean says, “Pash was involved in intelligence, whereas Berg was involved in spying and all the romanticism that goes along with that.”

Despite his lackadaisical attendance record and general disregard for orders from his superiors, Berg was an effective agent. Kean says he “did a good job gathering technical information” from European scientists, including Antonio Ferri, Lise Meitner, Paul Scherrer and Edoardo Amaldi. Berg, in essence, weaponized both the disarming demeanor he’d perfected by telling stories in the bullpen and the assorted knowledge he’d acquired from years of incessant curiosity to cut through the defenses of his targets. During a period of intense intellectual isolation—Amaldi was the only University of Rome physicist not to leave fascist Italy during the war, and the Jewish Meitner fled Germany for Sweden in 1938—Berg was an individual who could listen to these scientists and, for the most part, understand them.

Berg’s crucial contribution to the war cause, Kean suggests, was that he could offer Oppenheimer, General Leslie Groves and other Manhattan Project leaders “reassurance in some ways that there wasn’t something [they] were missing” regarding a potential German bomb.

Beyond these intelligence-gathering operations, Berg successfully persuaded numerous scientists to come to the U.S., either for extended visits or permanent relocation. News of Berg’s recruitment efforts reached the top of the government command chain, inspiring Roosevelt to joke, “I see Berg is still catching pretty well.” Most notably, the catcher-turned-spy arranged a tour of American educational institutions for Scherrer and got Ferri to accept a position at the National Advisory Committee for Aeronautics in Langley, Virginia.

Moe Berg, assassin?

By 1944, intelligence gathered by the Alsos mission suggested the Nazis’ nuclear program posed little danger to the Allies. But Heisenberg, the undisputed leader of German physics, remained at large, meaning the threat couldn’t be fully dismissed. The OSS considered and ultimately passed on numerous proposals to kidnap Heisenberg, including one in which a former Los Angeles cop was assigned to seize the scientist, smuggle him out of Germany into Switzerland and parachute out of a plane into the Mediterranean Sea, where a waiting submarine would whisk the pair to safety. Ultimately, the OSS settled on a different man and plan: Berg was going to Zurich.

Armed with a .45 caliber pistol and a cyanide capsule, Berg was, in the words of Dutch physicist and Alsos mission scientific liaison Samuel Goudsmit, expected to render Heisenberg “hors de combat” (French for “out of combat”) if he heard any indication that the Nazis were close to building an atomic bomb. Berg had three opportunities to assassinate the scientist: at Heisenberg’s December 1944 talk, during a subsequent reception dinner hosted by Scherrer and while walking the German back to his hotel. But the spy never took his gun out of his pocket.

The traditional narrative, as outlined in Robert Rodat’s 2018 biopic, The Catcher Was a Spy, holds that Berg listened to Heisenberg’s talk about a totally unrelated topic in physics, gleaned that the scientist was either anti-Nazi or unbelievably behind in the race to harness nuclear energy, and felt it was unnecessary to execute him. As Rodat told the New York Times in 2018, Berg “sensed when a runner was going to steal, and even though Heisenberg was trying to hide it, Berg knew he was despondent because Germany didn’t have the bomb and was going to lose the war.”

Dawidoff points out that Berg’s German was rusty at best and that he had no formal education in physics. The spy probably relied on the facial expressions of Scherrer and other scientists in the room to gauge the tone of Heisenberg’s lecture, if not the content. “Berg wasn’t exactly sure what he had heard,” writes Dawidoff, “but it didn’t seem terribly threatening, and nobody else seemed to find anything amiss either.” Kean, for his part, says the OSS was “really taking a gamble giving [Berg] a gun, period, much less expecting him to commit an assassination in public. … There is almost no chance he would’ve gotten away with it.”

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Two years after World War II ended, Truman decided to replace the dissolved OSS with the CIA, a more organized, accountable intelligence agency. Only 1,300 of 13,000 agents were selected to retain their positions in the new organization, and Berg was not among them. He’d resigned from the Strategic Services Unit, the intermediary organization that housed espionage activities during the transition to the CIA, after officials started hounding him to explain the nearly $20,000 of government funds he’d spent on his European missions, but “the truth is that he had been cast aside, and he still pined for the work,” according to Dawidoff.

In late 1946, President Harry S. Truman awarded Berg a Medal of Freedom. But the spy rejected the honor, which only vaguely referenced his wartime service due to the classified nature of the work. Writing that “the whole story of my humble contribution [cannot be] known or divulged,” Berg went so far as to say that “the medal embarrasses me.” Instead of a tangible souvenir of his accomplishments, the medal would be a constant, bitter reminder that his wartime adventures and his career in espionage were over.

Berg never lost his zest for the nomadic life. Except for a few odd jobs and an unsuccessful 1952 CIA mission to investigate the Soviet nuclear program, he never worked again. Instead, he wandered from place to place, relying on the generosity of strangers, old friends, distant acquaintances and what family he had left. Until his death at age 70 in 1972, Berg, the loquacious baseball player from New Jersey who became the subject of international intrigue, remained his own man. His last words, according to the National Baseball Hall of Fame, were reportedly shared with a nurse treating him after a fall: “How did the Mets do today?”

Zachary Clary | | READ MORE

Zachary Clary is a graduate student specializing in 20th-century politics and African American history at Vanderbilt University.