There’s a magical moment in historical research where the person you’re talking to, the descendant of your subject, apologises that they can’t really help you much, but adds that they do have a few things. At this point, they pull out a shoebox, in which their ancestor’s papers have lain undisturbed for decades. “Is that any use?” they ask, as you leaf gingerly through letters, certificates and photographs, and you reply that it is quite interesting, yes, all the while offering silent prayers of thanks that the contents have survived the fires, floods and house moves of the intervening years.

Shoeboxes are small, sturdy and ubiquitous. And in attics and cupboards around the world they sit, neglected, keeping their forgotten stories. Hadley Freeman’s House of Glass begins with a shoebox at the back of her dead grandmother Sala’s closet in Florida. Freeman, a fashion journalist, opened it while researching an article about Sala’s clothes. It contained a collection of mysterious photos and papers that hinted they might start to answer the question that had troubled Freeman since her childhood: why was her grandmother always so sad?

Svenja O’Donnell, another journalist, had a similar question about her own grandmother, Inge. An aloof, critical woman, Inge, like Sala, struggled in the role of granny. She only began to open up after, as an adult, O’Donnell made a trip to Kaliningrad, where Inge had lived decades earlier. Gradually Inge began to reveal to her granddaughter the story that she’d never told her daughter.

Both books are about the Second World War, but not as we are used to thinking of it. This isn’t the war of men charging up beaches or guiding Spitfires through the sky. Neither book is a tale of exceptional heroism or acts that changed the course of history. Their shared power lies in the very ordinariness of the two central women, each of whom did change her family’s story, simply by surviving.

Freeman’s story feels in some ways more familiar: a European Jewish family’s tale of escaping, or not, the Holocaust. It contains plenty of astonishing moments, including the brother who, released from a prison camp to visit his baby daughter, returned to the camp afterwards, because he had promised to. But at the heart of it is the relationship between Sala and her brother Alex.

By the 1930s, they had already fled one country, leaving the pogroms of Poland for France. In Paris, Alex had built himself a life as a dress designer, seemingly by force of personality. Sala too worked in fashion, designing patterns for fabrics. She was happy, and in love.

But Alex was convinced she wasn’t safe, and in 1937 he introduced her to an American millionaire, who wanted to marry Sala and get her, and the rest of the family, out of Europe. Sala eventually agreed. As a woman, she could save her family by marrying a man she didn’t love. But when she reached America, she would discover that Alex had deceived her.

While Sala’s family was threatened by the German advance of 1940, it was the Nazi retreat of 1945 that put Inge in danger. We’re used to thinking of this as a time of liberation, but for Germans on the country’s Eastern frontier it was the reverse. As the Red Army closed in, Inge realised she must flee, along with her small daughter and her parents.

O’Donnell heard most of the ensuing story from her grandmother, in stages, over the space of years. Freeman had to assemble her tale from archives and written memoirs. Each approach has problems. Archives contain only what was considered important enough to write down at the time, and little of Inge’s young life would have passed that bar, including few of the most significant moments. On the other hand, memory shapes and rewrites history through the lens of later events. Freeman, equipped with a memoir from her great uncle, was aware of his habit of self-mythologising, and conscious of the need to find contemporary corroboration.

Shoeboxes too are selective. First, they contain what we choose to cling on to. There will be few containing the names of the neighbours we denounced to the secret police. Second, terrible as both Sala’s and Inge’s stories are, they are the tales of those who survived. As Inge fled across the Baltic Sea, the ship behind hers was torpedoed. The refugees on board had their own stories, but they never had granddaughters to tell them. The shoebox in O’Donnell’s story comes towards the end, carrying a final secret so shattering that Inge had been unable to speak it.

Guilt echoes down both stories. For Freeman, it’s the Jewish guilt of having survived, having assimilated into the culture of the adopted country. For O’Donnell, it’s the German guilt of not having spoken out against the regime. Her great-grandparents privately opposed the Nazis, but stayed silent. Did they understand what was happening to Jewish families like Sala’s? “They knew,” Inge said. “But did they not want to see.”

That human determination not to see plain truths is another theme of both books. When a young German aristocrat gets Inge pregnant, his father stops them marrying by sending his son to the Russian front — a strange idea of what constitutes the greatest threat to the young man’s future. Her father begins his life as a refugee clutching the paperwork for a house and business that are worthless. Meanwhile, it wasn’t only Germans who declined to see the Holocaust. Sala’s brother Jacques refused to accept what was happening even as his family begged him to hide.

The stories matter for their contemporary echoes. O’Donnell’s reminds us that the refugees on the borders of Europe once had lives that were not so different from our own: homes, jobs, everything that seems solid can be snatched away. Freeman’s helps to answer a question occasionally posed in recent British arguments about antisemitism: what are Jews so worried about? Sala’s brother Alex survived the war and lived out his life in France a successful and wealthy man. But he never trusted the French again: his neighbours had turned on him before, and he knew they could again.

Like Sala and Inge, he had put his past away, but it was still there at the back of the closet, waiting in a shoebox, in case he wanted it again.