would rather not shake hands with a German of my age,” says Colette Marin-Catherine. “But I give all possible credit to the generations that came after.” There is steel in the elderly voice, but no anger. When Colette was 16, her older brother, Jean-Pierre, was deported to a German concentration camp. He was put to work as a slave labourer in underground tunnels assembling V2 rocket-propelled bombs. He died weeks before the camp was liberated by US soldiers. Brother and sister had both been active in the French resistance, but Colette escaped capture. She refused to set foot in Germany for another 74 years. Last year, Colette was persuaded by a young French historian to end the personal boycott and visit the site of her brother’s death. Their trip together is the subject of a short film, Colette, released this week. It is a portrait of an intimate grief, locked away for decades, then entrusted to younger hands for safekeeping. It is one victim’s story, redeemed from the anonymity of mass slaughter, pulled from the tide of forgetting. The witnesses will not be with us for ever. “Remember, I am 92 years old,” Colette tells me from her apartment in Normandy. “If you have something to ask, you had better take the opportunity now.” This week is also the 75th anniversary of the start of the first Nuremberg trial of Nazi war criminals. A military tribunal in the smouldering ashes of war was not the perfect court, but the reckoning had to begin somewhere. Nuremberg was the site of annual Nazi rallies. “Nuremberg laws” were the legal blueprint for genocide. It was the right place to put the monstrosity of the Third Reich in the dock, but the task demanded a new apparatus of international justice, a new vocabulary of rights common to humanity. The Europe we have now is just one of many that might have crawled out of the abyss in 1945. It describes a choice: cooperation and integration over nationalism and militarism. How probable was that outcome? Chaos and war were the precedents. It was not obvious to Colette as a teenager that she would live to see the frontier between France and Germany dissolved. “Now it seems normal that the era of frontiers is obsolete,” she says. “You can try to stop people, but you cannot stop money crossing. You cannot stop a virus. What is it for, this border? You tell me.” The founding story of the EU, the boring miracle of reconciliation through trade, has never resonated in Britain for various reasons. The European project was viewed with disdain until its success provoked envy. UK accession in 1973 was sold to the public as a remedy for economic decline, even by those in favour. It sounded like Britain was capitulating to pushy continentals. That ambivalence is conveyed in a 1979 interview with Margaret Thatcher lamenting Britain’s lack of competitive edge. “I can’t bear it,” she says. “We, who either defeated or rescued half Europe, who kept half Europe free when otherwise it would be in chains! And look at us now!” Thatcher went on to drive the creation of the single market – a huge achievement now cherished by the European commission and rejected by the current Tory prime minister. But Brexit was never about economics. The promise was independence, which could never be realised because there was no enemy imposing dependency. The relationship with Europe is vital, not coercive. But accepting parity with Germany, even in the 21st century, seems to animate some atavistic fear of losing the moral distinction between winners and losers in 1945. The Brexit fantasy of resistance against tyranny is grotesque when set against the sacrifice made by people such as Colette, who defied fascism when it kicked down their doors. Britain basks in the luxury of not knowing how it might have responded to occupation, although the Channel Islands are a guide. The pattern of collaboration there was the same as everywhere else. Meanwhile, the Home Office monitored hundreds of Nazi sympathisers across Britain. Eager fifth columnists sought out Gestapo agents, hoping to be recruited for sabotage missions. “Don’t forget, man is wolf to man,” Colette says. “In every country, in every civilisation and for as long as the world has been around.” The contagion of hatred that she witnessed as a child was not confined to a historical moment. “It’s like Covid. It can appear anywhere.” Memory is the vaccine, preserved in memorials, transmitted down generations in the hope of reaching herd immunity. But if it is not taken up, and witnesses fall silent, the antibody count in the cultural bloodstream declines. The idea of “Europe” as a peace project is already becoming a museum piece in Britain, a sepia-toned ambition in a glass cabinet, admired by the few who seek it out. David Cameron referred to it once in a speech during the referendum campaign. “Europe had a violent history. We’ve managed to avoid that, and so why put at risk the things that achieve that?” The leave campaign ridiculed the speech. Boris Johnson said Cameron was conjuring the threat of “German tanks crossing the French border”. The remain side dropped the subject. No member state is hurrying to follow Britain’s example, but European idealists worry about the gap between political reality and the ethical foundations of the project. Liberal democracy is being hollowed out by ultra-nationalists in Hungary and Poland. Far-right parties across the continent have seeded the mainstream with their interpretation of Europe as a white Christian entity under siege by encroaching Islam. They cultivate nostalgia for a lost era of ethnic homogeneity, and demand integration from the religious minority, glossing over the story of how Europe made itself more Christian by murdering Jews. Assimilation was no sanctuary. Liberal politicians in EU capitals are better at expressing alarm about that tendency than finding strategies to reverse it. British Eurosceptics revel in continental disunity because it supports their view that the whole enterprise is unsustainable. Since there is no economic benefit from Brexit, its dodgy prophets crave vindication in a great unravelling that they can then claim to have foreseen. Absent from British politics is any account of what happens if the prophecy was wrong. What if memory triumphs over forgetting, and the European project is resilient? There is a Brexit story that casts the EU as a basket case – a burning building from which Britain escaped just in time – and there is a Brexit story that casts Brussels as the tyrant that hoards sovereignty. The leavers have no concept of European success – no map for Britain to advance alongside an EU that sticks to the path that it took out of the abyss 75 years ago. What if a plan for stability and prosperity through peaceful cooperation works? That is a future Brexiteers cannot imagine, because it is the past they chose to forget. • Rafael Behr is a Guardian columnist • The film Colette, directed by Anthony Giacchino and produced by Alice Doyard, was commissioned by Guardian Documentaries