In Aistersheim, a village in north-west Austria, a pale yellow castle towers over a frozen lake, as if out of a fairy tale. It looks like it might be awaiting royal guests. But the sign at the entrance reads: “Congress of the defenders of Europe.” I had signed up under a false name, because only the “well-wishing” press was allowed to attend this gathering in March of far-right activists, mostly from Germany and Austria.

Under the ribbed vaults of a large hall, I join an audience of 300. The first speaker is the deputy mayor of Graz, Mario Eustacchio, from Austria’s far-right Freedom party. He lashes out against what he calls modern obsessions with “human rights”, which he says have produced a “catastrophic situation in Europe”.

Today’s far right wants to downplay Nazi crimes as a first step towards reawakening ideas from that era

Next is André Poggenburg, the regional head of the German far-right Alternative für Deutschland party in Saxony-Anhalt. He calls for a “Gerxit”, Germany’s departure from the EU. He wants a “fortress Europe” that will ally with Putin’s Russia – a regime clearly admired in these circles. A blonde woman wearing a satin dress stands up to sing German and Russian patriotic songs. Another AfD member follows. He uses the word Mitteldeutschland (central Germany) in reference to former East Germany – as if more German territories lie beyond the Oder-Neisse line which has marked the border with Poland since the second world war. After that, an Austrian publisher complains about “censorship” of the word Neger (negro).

Later, there are speeches by self-styled “alternative media” representatives, who explain that infiltrating social networks helps “influence public opinion”, for example by posting insults on Angela Merkel’s Facebook page. And to top it all off, a youthful, elected politician from Italy’s South Tyrol calls, hand on chest, for his region to be annexed by Austria.

Stepping out for some fresh air, I stroll around some stalls showcasing various publications, including those of Les Identitaires, a racist French group calling for a “white Europe”. Other books carry titles such as Race, Evolution and Behaviour, or The Young Hitler, A Corrected Biography. I pick up a copy of The Brainwashing of Germans and its Lasting Consequences. It is the opposite of the message I wrote in a book (Les Amnésiques) about Germany’s postwar transformation and its efforts to deal with its Nazi past, through the story of my own family.

Géraldine Schwarz’s German grandparents. Her grandfather was a member of the Nazi party.

I am the granddaughter of a German member of the Nazi party and of a French gendarme who served under the Vichy regime, which collaborated with the Nazis. My German grandfather was not an ideological National Socialist – he joined out of opportunism and for convenience. He took advantage of Nazi “Aryanisation” policies to buy a Jewish family business at a low price. My grandmother was not a card-carrying Nazi, but was fascinated by the Führer. Between them, they were typical of the Mitläufer (followers): those masses of people who, through blinkered vision and small acts of cowardice, helped create the conditions for the Third Reich to perpetrate its crimes.

After 1945, Germany’s trickiest task was not setting up new institutions or prosecuting high-profile criminals – it was transforming the mindset of an entire population whose moral standing had been reversed by Nazism in ways that made crime appear not only legal but heroic. My grandparents never acknowledged their responsibilities as Mitläufer. But their son, my father, became part of a generation that confronted its parents and forced Germans to ask themselves: what did I do? What could I have done? How do I act now?

The Holocaust Memorial in Berlin. Photograph: Alamy

One of the greatest achievements of the memorial work Germany has undertaken since the 1960s has been to infuse many of its citizens with a historical conscience and a sense of duty towards democracy, as well as a critical attitude towards populism and extremism both left and right. In France, the taboo long attached to how people behaved under Vichy made such teachings more difficult. In Italy, Austria and eastern Europe, efforts to reckon with their past as allies of the Nazis were even weaker. It is no coincidence that these are countries where patterns of extremism we’d thought long gone have returned.

But now, Germany in turn is affected. Last September, 12.6% of voters cast a ballot for the AfD, allowing a far-right party to secure a strong position in parliament for the first time since the second world war. The arrival of more than a million refugees seems to have broken down the safeguards. In former East Germany – where no true reckoning of the past was possible under communism because state propaganda held West Germans solely responsible for Nazism – the AfD’s popularity was twice as high as in western parts of the country.

What worries me most is that younger generations in Germany and elsewhere feel less and less concerned with the history of fascism, and hence risk becoming indifferent to the new threats. That’s precisely what the AfD strives for when it says it wants a “180-degree turn” from the tradition of atoning for Nazism, and suggests the Holocaust memorial in Berlin should be closed down, and Wehrmacht soldiers rehabilitated. It’s also what the Austrian FPÖ has in mind when its MPs refuse to applaud a speech commemorating the 1938 Kristallnacht massacre.

Today’s far-right parties want to downplay Nazi crimes as a first step towards reawakening ideas from that era: the notion that a hierarchy can be drawn among humans according to their race or their religion, the acceptance of violence and hatred, mendacious propaganda and devotion to a strong leader. “Empathy is a weakness” was the motto of the SS.

We have to give young people a knowledge of the past, and a pride in belonging to a continent where two totalitarian systems were ultimately defeated. Democracy in Europe was built through blood, sweat and tears – the dignity of citizens was eventually restored. Now is the time to remember.

• Geraldine Schwarz is a Berlin-based German-French journalist and author of Les Amnesiques (published in France by Flammarion and in Germany by Secession Verlag)