The end of the Second World War wasn’t just supposed to be a definitive military moment, but also a victory over tyranny. A triumph over the Nazis, and their terrible brand of extremism and hatred.

So, as we mark the anniversary of D-Day, it’s reasonable to wonder if the victory has lingered, or whether the sacrifices are now ebbing away.

As 80 years have gone by since D-Day, does Europe still remember the people it once promised never to forget?

Auschwitz, Dachau and all the other grim monuments to the Holocaust are still there, but antisemitism has never really gone away.

In fact, it has increased hugely over the past six months, driven by antipathy towards the Israeli government that has morphed into abuse towards Jewish people in general.

But, even before the war in Gaza, the internet still teemed with ludicrous claims about Jewish bankers controlling the world – the sort of stories that would be absurd if they weren’t so troublingly similar to the propaganda spouted by Goebbels in the 1930s.

Echoes of the past do reverberate. In Spain, there is a lingering nostalgia for General Franco, with one political party – Vox – seeking to rehabilitate the reputation of the one-time dictator.

In Italy, the prime minister, Giorgia Meloni, represents a party that owes its roots to fascism and, while Ms Meloni has distanced herself from that history, there is a sense that the hard lines of the past have been softened by her success.

Just a couple of months ago, hundreds of people gathered to mark the death of Italy’s war-time fascist dictator Benito Mussolini, all of them – repeatedly – giving an orchestrated fascist salute.

In Germany, that would be illegal. In Italy, it simply… happened.

Across Europe, parties based on populism, nationalism, far-right rhetoric – or a blend of all that – are on the rise. Trust in mainstream politicians is tumbling. Extremism is on the rise.

So is this just a political blip? Or, with an eye on the 6 June anniversary and the Second World War, should we be worried that Europe is once again beginning to look like a dangerous, explosive crucible?

I spoke, in confidence, to some senior diplomats from across Europe, to canvass opinions.

I had expected them to tell me that the question was an over-reaction – that there was really nothing to worry about.

Instead, each confessed to concern.

“It’s something I’ve been thinking about a lot recently,” said one. “I don’t think it’s directly comparable to the 1930s, but there are definitely echoes.”

What each said was that they saw the growth of extremism as being allied to a sense of disillusionment with mainstream politics.

“For decades, politics has been fought in the centre, so you end up with big parties who say quite similar things about society and economics,” one diplomat told me.

“Then you get a period of economic problems, especially when it comes at the same time as a pandemic and a war, and some people want more radical solutions.

“On top of that, you’ve got young people who, quite naturally, don’t want to just follow the path of their parents.

“We’ve seen this huge rise in politicians focusing on deliberately vague ideas about identity and sovereignty. And then there’s all the misinformation on social media.”

It’s impossible to talk about the rise of far-right and populist parties without talking about social media, which has done so very much to amplify conspiracy theories and volatile, divisive news agendas.

European voters who say their main source of news is social media are also the people most likely to mistrust the big institutions – not just politicians, but also the police, the health service, banks and mainstream journalism.

“My government doesn’t want to dive into TikTok because of the links to China and to dubious characters like Andrew Tate,” says another diplomat.

“But that’s left the way clear for other politicians to dominate. And so we’re leaving the way for extremists to have a huge influence on a mainly young audience.”

France’s Rassemblement National (National Rally), of which Marine Le Pen is parliamentary leader, has invested hugely in social media, including TikTok.

Jordan Bardella, the party’s president, has 1.3m followers on TikTok – three times the number who follow him on X.

You might say there’s a parallel there. The Nazis used propaganda in ways it had never been used before, not least in the way they relentlessly focused on the innate greatness of Germany, and the danger posed by Jews – portrayed as “outsiders” determined to undermine the country.

Now, it’s migrants who are the focus of so much attention, invariably portrayed as a problem and often described as a danger.

Just look at the number of people who came on to the streets the other day in the company of Tommy Robinson.

At a time when politics can appear vague and complex, there are always those attracted by a one-theme polemicist.

But if there was one big political theme of D-Day, it was the idea that it was the triumph of democracy over totalitarianism.

Since then, Europe – and so much of the Western world – has embraced and adopted democracy as its norm. But there is nothing that says this will last forever.

Authoritarian regimes, not least Russia, have spent vast amounts on trying to discredit European democracy, and it might just be working.

While most people still prefer democracy to anything else, young people seem to be more willing than anyone else to countenance the idea of living under authoritarian governments.

Youngsters, in their late teens or early 20s, are twice as likely to support the idea of a military regime than old people.

And there are countries where the rule of law has been undermined – Hungary and Poland among them.

The Balkans remains a volatile area and, if the erratic Serbian president Alexander Vucic ever does decide to send troops into Kosovo, we can find ourselves in another conflagration.

Transnistria, the pro-Russian enclave that sits between Moldova and Ukraine, is another potential flashpoint. So, too, the disputed territory between Azerbaijan and Armenia.

But Europe does have bulwarks now that didn’t exist in the 1930s.

The European Union, for all its flaws, brings its members together and forces them to confront problems.

NATO has transformed the military view of Europe, maintaining unbroken peace between its members.

International law is maintained by independent bodies.

So maybe the problem isn’t that democracy, or European safety, is fundamentally broken.

But maybe it isn’t delivering what the people want. Which is, after all, the purpose of democracy in the first place, isn’t it?

It’s not the 1930s. There are no Nazis in power nor any genuine fascists. Europe is a safer, more solid and predictable continent now.

But it is a more volatile continent today. War in the east; political tremors in all corners. And a widespread desire for change.