Barbara Keller remembers the summer day in 1945 when her mother suddenly told her they were about to flee to Germany. Their homeland would cease to exist in the mayhem after World War II.

"We had to leave in one hour," said Keller, then seven and living in what today is part of the Czech Republic. Allowed to take only one toy, she grabbed her doll while her brother, two years older, picked his favourite teddy bear.

"Seventy years have passed, but I'm surprised at how this still brings tears to my eyes," said Keller.

Today's scenes of hundreds of thousands of migrants arriving by train in Germany have brought back traumatic memories of her own family's flight.

"I see myself as a refugee with nothing, just a bag," said the former kindergarten teacher with piercing blue eyes.

Born in August 1938, Keller grew up in Reichenberg, to the north of Prague, the border regions of then Czechoslovakia.

Known as Sudetenland, the area had an ethnic German minority of three million, including Keller's family. Barely two months after she was born, Adolf Hitler annexed it as part of Nazi Germany.

But after the Nazis' defeat, the region was returned to Czechoslovakia, which quickly began expelling ethnic Germans.

Keller was one of the millions suddenly left homeless, like the migrants flooding into Germany today whom the 77-year-old has no doubt should be given help.

"We have to offer them protection, give them something," she said, noting that the show of generosity by many Germans underlined the fact that they had "themselves once lived through" such scenes.

Keller has donated clothing and other essentials but feels that getting directly involved with the new arrivals was too big a step for now. "I don't know how I would react. I don't want to scare them by breaking down myself."

She acknowledged that her integration decades ago was probably far easier than for the hundreds of thousands of Syrians, Iraqis or Eritreans who have fled war or misery. She faced neither  language barriers nor cultural or religious differences.

But the trauma of the flight has never been shed and is still rarely discussed within the family.

- 'People without roots' -

At such a tender age then, Keller could not fathom why her life was suddenly upended. Her family spent the first several weeks in a camp before her mother decided to flee to neighbouring Bavaria -- several hundred kilometres away.

The route was circuitous; sometimes they trekked by foot, other times they travelled on cattle cars on trains.

"We headed to the border, but Russian soldiers there sent us back. My mother had all the documents and stamps possible, but they said that they were not valid," Keller recalled, tapping her fingers nervously.

Finally they reached a village where a farmer tipped them off about a passage to the border.

After almost a night crossing fields and a forest, "in the morning, I saw a tent and an American flag... that was October 14, 1945."

That day has since become a day of celebration for her family.

Their final destination was the Royal Villa of Regensburg, a meeting point her uncle had set in case there were problems after the war.

In those days like today, refugees were put up in school gymnasiums. Authorities were urgently looking for available shelter, with every unoccupied space quickly seized. In one Bavarian village, the word circulating among inhabitants was "keep quiet or the mayor will put refugees in there".

Keller's mother eventually found a job as a teacher with lodgings in the school. "We felt good for the first time to have four new walls, even if they were empty," recalled Keller.

As an adult, she eventually went on to live in England, France and Luxembourg, before returning to Munich in the 1970s so that her sons "would feel German".

But as it turned out, "they feel more like Europeans" -- one spent several years in Paris, while the other lives in Chicago.

"Probably because we are people without roots," said Keller.