The Nazi kidnapping of hundreds of thousands of ‘Aryan’ children from Eastern Europe is, in the words of Polish writer Artur Wróblewski, a ‘white spot’ in historiography. ‘Hardly any other topic in German-Polish historical research’, writes Wróblewski in his book, As If I Were Alone in the World, ‘has so many gaps.’

One arresting reason why this Nazi crime remains underexplored is that many of its victims were or remain unaware. Tens of thousands of Eastern European children seized from their families during Nazi rule are thought to be alive today, still living in Germany, entirely unconscious of their origins.

While estimates vary, it is generally thought that the Nazis abducted up to 400,000 ‘Aryan’ children during the Second World War from a host of countries, including Ukraine, Yugoslavia, Czechoslovakia, Romania, Estonia, Latvia, and Norway. By far the biggest campaign – accounting for over half of all abductions – took place in Poland.

Children recognised as ‘bearers of blood valuable to Germany’ were taken from the streets, playgrounds, schools and even their own homes. The operation – conceived personally by SS leader Heinrich Himmler – served a dual purpose: depleting the population of countries the Nazis were conquering and replenishing Germany’s own population with ‘racially valuable children’.

In late 1939, after Germany had conquered Poland, Himmler gave a speech to a restricted audience of SS members in which he laid out the Nazis’ plans for Poland: ‘The population [of occupied Poland] will become a permanently inferior race which will be available to us for slave labour.’ But, he continued, ‘a fundamental question is the racial screening and sifting of the young. It is obvious that, in this mixture of people, some very good racial types will appear from time to time’.

The quest to filter out the ‘racially valuable’ from those deemed to be worthless was essentially an attempt by Nazi officials to identify children who they believed were descendants of German settlers who had emigrated to Poland. ‘Our own blood has flowed into a foreign nationality through the vicissitudes of German history… we are convinced that our own philosophy and ideals will reverberate in the spirit of these children who racially belong to us,’ said Himmler in May 1940.

Himmler was also clear that this abduction campaign should focus on those younger than ten. Only this cohort were ‘capable of Germanification’, he reasoned, since after this age it would be impossible ‘to truly change their national identification’.

By late 1941, temporary centres had been set up in both Germany and its conquered territories, where abducted children with ‘racial potential’ would be taken for examinations, and assessed according to their body proportions, eye colour, hair colour, and the shape of the skull. In the next phase, those deemed of value were sent to children’s homes in the ‘old Reich’ to be ‘re-educated’ and ‘Germanised’, before being given to law-abiding and Nazi-supporting childless couples.

In a secret paper, the Nazi Office for Race and Resettlement (RuSHA), which supervised the project between 1939-41, announced that new birth certificates, as well as German names of Teutonic origin, should be issued to the children to conceal their true identities. Crucially, even their new German adoptive parents should not be told the truth about their origins. ‘Particular care must be taken’, a secret 1941 order from Poland’s central SS office concluded, ‘to ensure that the term “Germanisable Polish children” does not come to public knowledge.’ Instead, adoptive families were led to believe that they were rescuing ethnically German children from ‘the regained Eastern territories’ who had been orphaned by the war.

Even after the end of Nazi rule, returning abducted children to their original families was a colossal task. Following Germany’s defeat, the United Nations Relief and Rehabilitation Administration (UNRRA) – established by the Allies in 1943 to provide relief to those ravaged by war – launched a campaign to search for the children stolen by Hitler. These efforts included the establishment of a Central Tracing Bureau in Arolsen, the small town in the British Zone of occupied Germany where the UNRRA headquarters was located.

Over the months following the end of the war in Europe, information began to flood into the Bureau from family members – above all from Poland, the Baltics and Ukraine – about their children who had been taken away from schools or their homes by the Nazis. UNRRA relief workers would go from house to house canvassing, equipped with nothing but tens of thousands of snapshots of babies, toddlers and young children, alongside descriptions provided by their original families of when and how they had disappeared. That their names had been changed – and, in some instances, false birth certificates drawn up to obscure their identities – made tracking down these children a formidable task. The task was further complicated by the Nazi order in April 1945 that all German documentation for Hitler’s child abduction programme should be destroyed.

Crucially, correctly identifying stolen children was only the first hurdle to overcome. When it came to repatriation efforts, a deeper moral challenge arose from the fact that the native countries of so many of these stolen children had become entirely foreign to them.

The personal account provided by the Austrian-born historian Gitta Sereny of her years working as a UNRRA child welfare investigator in the aftermath of the Nazis’ defeat is illuminating. As Sereny later explained in her book, The German Trauma, stolen children who were successfully tracked down in Germany often did not want to return. In many cases, younger children did not speak their birth language and had no memory of their original life or family. Older ones had, in some cases, been taught to hate their native countries.

UNRRA psychiatrists would work with these children in Germany to help them recover memories of their original families, with some success. Polish nursery rhymes, Sereny recalls, proved particularly effective in reawakening early memories. Even so, what comes across most strikingly of all in Sereny’s account is her profound sense of guilt. She reveals her own inner moral conflict as she describes both her desire to do good work, and her deep feelings of unease as distressed children were ripped away from families for a second time – often the only family they could remember:

‘The task [of removing the stolen child] was never anything but traumatic… I will never forget the inconsolable grief of the couple who loved the five-year-old I had to take from them, and the wild anger of the child who had no memory of his birth parents or native language, and for whom his German parents were his world.’

All of the German adoptive parents Sereny encountered were, at least as far as the UNRRA could determine, unaware of the violent methods by which the child had come to them. They appeared to have raised these kidnapped children – who were often their only children – in loving environments and, unsurprisingly, fiercely resisted giving them up. ‘What was the “right” solution to this human conundrum?’ asks Sereny:

To return the children to parents who longed for them, but in an impoverished and largely destroyed Eastern Europe, and to an ideology unacceptable to many of us? Or should we leave them with their loving German second families – our immediate past enemy, with their lingering love for Hitler – who had obtained them as beneficiaries of a crime of truly biblical proportions? What was in the best interest of the children?

Some of the testimonies provided by kidnapped Polish children at the eighth Nuremberg trial would do little to ease Sereny’s concerns. During this trial, children who were successfully traced and returned, postwar, to surviving family members in Poland testified, including Barbara Mikołajczyk, who was tracked down by an aunt and brought back at the age of 10 to Poland, where she was unable to speak her native language.

Mikołajczyk recalled the difficulty of re-integration – not only because she missed her old life in Germany but also because of the rejection she faced from Polish peers, who simply viewed her as German. Consequently, Mikołajczyk, who later became chair of a group that called itself the ‘Association of Polish children who were Germanised by the Hitler Regime’, said she felt as though she became a scapegoat for all of the misery that Poles had endured during the war and the Nazi occupation.

The unease that Sereny also recalls feeling about returning children to ‘an ideology unacceptable to many of us’ touches on another tension surrounding the repatriation of the Second World War’s stolen children. Sereny herself hastens to qualify this by adding: ‘The Soviets had as much right to their children as anyone else.’ Yet there is reason to suspect that efforts to repatriate stolen children may have proven more successful were it not for rising tensions, and mutual mistrust, between East and West at the dawn of the Cold War.

In the summer of 1947, the Americans decided to wind down the department responsible for searching for abducted children at UNRRA. When Allied efforts to identify such children ceased, 13,517 inquiries were still open. Some argue that efforts to track stolen children were curbed prematurely. This is almost certainly in no small part a consequence of the growing unease felt by the US and British authorities about sending children behind the Iron Curtain – and their increasing reluctance to co-operate with the USSR and its vassal states still looking for missing children.

There is no exact record of how many stolen children were ultimately identified and resettled. It’s thought that only around 40,000 of the 200,000 Polish children stolen by the Nazis were ever returned home. Thousands more still live in Germany today, unaware of their true identity and heritage. Countless parents from Eastern Europe lost their children forever.

As for the aforementioned 40,000, one cannot help but wonder how many of them wished that they had never been found.

The question of how to track down and repatriate children removed from their homeland during wartime has renewed relevance in Eastern Europe today. The Second World War’s stolen children are a troubling reminder that wartime abduction of children is a difficult wrong to right.

According to the Humanitarian Research Lab at Yale University, an estimated 35,000 Ukrainian children – the youngest just four months old – have been forcibly transferred to Russia and Russian-occupied territories since President Putin launched his full-scale invasion in February 2022. While Kyiv’s allies condemn this as wartime kidnapping, Maria Lvova-Belova, Russia’s child commissioner, insists that Moscow’s ‘evacuations’ are merely preserving a child’s ‘right to live under a peaceful sky and be happy’. She has applauded the efforts of Russian families adopting Ukrainian children, adding that the Ukrainian child she herself has taken in ‘does not let go’ of his newly issued Russian passport. Lvova-Belova has been open too about Russia’s ‘re-education’ efforts. Reporting to Moscow’s Civic Chamber on World Children Day, the ombudswoman cited the case of a group of 30 Ukrainian children brought to Russia from the basements of Mariupol, who had once defiantly sung the Ukrainian national anthem and shouted, ‘Glory to Ukraine!’. Now, with time, effort and the help of psychiatrists, ‘all their negativity’, she insisted, has ‘transformed into a love for Russia’.

Researchers at Yale have described the removal of Ukrainian children as ‘likely the largest child abduction in war since the Second World War – comparable to the Germanification of Polish children by the Nazis’. Motivations differ, and much remains unclear about the exact circumstances in which many of these Ukrainian children were removed – or how many were already orphans as opposed to being ripped away from family members.

Regardless, Second World War Germany is a salient reminder that, when it comes to postwar repatriation, the logistical challenge of tracking down children is just the first hurdle to overcome. Next comes a deeper moral challenge, especially when dealing with those too young to retain any memories of their first language or family.

It is one thing to speak of returning children home, quite another to know what constitutes ‘home’ to them.