Parents gave their children advice and checked them over one last time. Then, came the goodbyes—sincere, but not too sad. “There was laughter and crying and one last hug,” recalled social worker Norbert Wollheim. The Jewish children, clutching their possessions, then walked toward the train to become child refugees in England. Their parents stayed behind.

The parting may have been understated, but its consequences were not. For most of the children who left Germany in scenes similar to the one Wollheim recalled, it was the last time they ever saw their parents. They were part of the Kindertransport, or children’s transport, a rescue effort that brought Jewish children to England in the lead-up to the Holocaust.

“We couldn't even foresee, we couldn't surmise for a moment that for many or most, it would be the last goodbye, that most of those children would never see their parents again,” Wollheim recalled in an oral history.

Between 1938 and 1940, about 10,000 Jewish children made their way to Great Britain on the Kindertransport. But though the rescue is widely seen as one of the only successful attempts to save European Jews from the Holocaust, the reality was much more complicated.

READ MORE: Holocaust Photos Reveal Horrors of Nazi Concentration Camps

The idea for the Kindertransport came after Kristallnacht, the anti-Jewish pogrom in which tens of thousands of synagogues, homes, and businesses were destroyed in November 1938. Life had been getting harder for Jews under Nazism, but Kristallnacht represented a turning point. After the violence, Jewish parents began desperately searching for ways to get themselves—and their children—to safer countries.

That wasn’t easy. The United States, Great Britain and other countries had strict immigration quotas and repeatedly refused to change their policies to help Jews under threat from the Nazi regime. At the 1938 Evian Conference, 32 nations had met to discuss what to do about the increasing number of Jewish refugees. But Great Britain, France and the United States had all left without committing to change their policies.

Kristallnacht, however, brought more attention to the plight of Jews within Germany and its territories. When public opinion in Great Britain turned, the British government finally shifted its policy toward refugees. If English refugee aid organizations would agree to pay for the care of refugee children, Britain agreed, it would relax its immigration quotas and allow Jewish children age 17 and younger to immigrate.

There were catches: The children couldn’t be accompanied by parents or any adults, and would have to leave the host country once the refugee crisis had ended. At the time it was inconceivable that within a few years most of Europe’s Jewish population would be murdered.

It took a major mobilization effort to get the children to Great Britain. Guarantors—people who agreed to pay for the children’s upkeep—had to be found for children who wanted to immigrate. (The government refused to use state dollars to support the children.) Usually, foster families were friends or family members in Britain, but they were also solicited in newspaper advertisements. “Please help me bring out of Berlin two children (boy and girl), ten years, best family, urgent case,” read a characteristic ad.

On December 2, 1938, the first Kindertransport arrived—200 children from a Jewish orphanage in Berlin that had been destroyed on Kristallnacht. On the way over the German-Dutch border, the train carrying the children was boarded by SS members who went through the children’s luggage. “As the SS men pawed through carefully packed clothes and toys,” writes historian Thomas J. Craughwell, “the children wept and shrieked in terror.” The children then sailed to Harwich, England on a ferry.

Orphans, homeless children, and the children of people in concentration camps were given priority on the transports, which lasted until as late as 1940. Many children were sent by their parents, too. Vetting of foster families was lenient when it happened at all. Some children headed to homes where they were abused or expected to act as servants.

Over time, the transports stoked increasing anti-Semitism in Great Britain. As fears of a German invasion grew, parliament passed legislation allowing the internment of “enemy aliens,” refugees thought to be pro-Nazi. “That many of the ‘enemy aliens’ were Jewish refugees and therefore hardly likely to be sympathetic to the Nazis, was a complication that no one bothered to try and unravel,” writes the BBC. Suspected enemies, among them teenage members of the Kindertransport, were incarcerated on the Isle of Man or sent to Canada and Australia. About 1,000, or one tenth, of the Kindertransport children were classified as enemy aliens.

The fates of the Kindertransport children varied dramatically. Some fought for Britain against the Nazis. Others reunited with family members after the war. But for most, the day they boarded the transport trains before World War II was the last time they ever saw their parents. For those who did reunite with their families, the transition was often difficult, and brought up complicated issues of familial assimilation, trauma, and even language.

Today, the Kindertransport looms large in Britain’s memories of World War II. But historian Caroline Sharples warns that it can be used as a way to glorify a country’s generous action without acknowledging the nuances of the actual situation—the adults who were turned away to die in the Holocaust, the traumatic experiences of children whose time in Britain was characterized by abuse and antisemitism, the mistreatment of so-called “enemy aliens.”

“For all of the popular fascination with the Kindertransport,” Sharples writes, “there remain a number of issues that need to be addressed more fully….the history of this scheme needs to be placed much more firmly within the broader, long-term context of British immigration policy.”

The story of the Kindertransport continues to evolve as survivor stories and historical revelations about the world’s reaction to the Holocaust are woven together. In December 2018, the Claims Conference, which negotiates with the German government for financial compensation for victims of the Holocaust, announced that Germany would make a one-time payment of about $2,800 to each surviving child of the Kindertransport.

“After having to endure a life forever severed from their parents and families, no one can ever profess to make [the survivors] whole,” a negotiator of the settlement, Stuart Eizenstat, told the Guardian. “They are receiving a small measure of justice.”

For survivors of the Kindertransport, their lives were forever altered by their flight from a hostile nation before the Holocaust.