He also recommitted to deporting millions of undocumented Mexican people, a move that further delighted his base and forced many of his few remaining high-profile Hispanic surrogates to publicly throw in the towel.

But while Donald Trump’s plans stand out for their toughness, he is not the first presidential nominee—or president—to call for such programs. Such deportation schemes have a long and tragic history, and Trump’s plan parallels a previous one executed by the Eisenhower administration called Operation Wetback. Yes, they called it that publicly.

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It is clear that candidate Trump knows about that program. Although he has been circumspect enough not to refer to it by name, he has praised it many times.

“Let me just tell you that Dwight Eisenhower — a good president, great president, people liked him…” he said during a Republican debate in November, 2015. “He moved a million and a half illegal immigrants out of this country, moved them just beyond the border. They came back. Moved them again, beyond the border: They came back. Then moved them way south. They never came back.”

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Trump’s rhetoric adds another chapter to a complex and little-remembered history that has been playing out in the lives of Mexican immigrants and Americans since the 1920s, when small family farms began to be replaced by larger, investor-backed operations, mostly in the Southwest.

These newfangled agricultural enterprises required a large and mobile labor base to remain profitable. Migrants from Mexico became a perfect solution — cheap, plentiful, and, because they weren’t citizens, ineligible to lobby for better working conditions.

Early anti-migrant programs appeared a few years later, a quarter century before the Eisenhower administration launched its unfortunately named version. NPR’s Code Switch covered an early scheme that played out during The Great Depression in the 1930s. Some two million people, including U.S. citizens, were rounded up in terrifying public raids and shipped to Mexico, for fear that they were taking scarce American jobs. In 2012, the State of California publicly apologized for its role in the event.

When it arrived two decades later, Operation Wetback was broader in ambition. The New Republic’s Jeet Heer explains, in a must read history, the moment it became necessary:

“In 1942, the Mexican and American governments tried to bring order to this exploitive system by agreeing to the Bracero Program (formally known as the Migrant Labor Agreement), which permitted vetted contract laborers (mainly screened for health problems) to be legal guest workers for a fixed term, usually a few months at a time. Braceros were promised fair treatment in wages and boarding, but enforcement was lax and employer abuse was widespread.”

Operation Wetback was initially supported by many advocacy groups that had become aware of the terrible conditions experienced by workers, as well as by many Mexican Americans who were concerned by the dampening effect the braceros had on their own wages. Agricultural employers, who routinely failed to comply with the new labor standards, were also eager to see the immigrants disappear. And as anti-Communist fervor took over the U.S in the 1950s, the porous border became a paranoid obsession. Every Mexican became a Communist in disguise.

The raids disrupted entire communities, destroyed families and legitimate businesses, and stoked deadly anti-Mexican sentiments. They were also horrific.

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In the go-to book on the operation, Impossible Subjects, historian Mae Ngai describes deportation ships that were later compared in Congressional reports to “eighteenth century slave ship[s]” and “penal hell ship[s].”

Others died as they were dumped across the border. “Some 88 braceros died of sun stroke as a result of a round-up that had taken place in 112-degree heat,” she wrote. “At the other end of the border, in Nuevo Laredo, a Mexican labor leader reported that ‘wetbacks’ were ‘brought [into Mexico] like cows’ on trucks and unloaded fifteen miles down the highway from the border, in the desert.”

So, yes, I suppose Trump is right in one regard. They never came back.

Ellen McGirt writes Fortune’s raceAhead, a daily newsletter about race and culture.