On Holocaust Memorial Day, a powerful new documentary, will be shown in more than 30 countries, from Australia to Zambia in what is being billed as “the widest-ever global theatrical screening event for a Holocaust documentary.”

Who Will Write Our History, honours Jews of the Warsaw Ghetto who opposed the Nazis’ attempt to wipe Polish Jewry from history with a bold act of cultural resistance. Written, directed and produced by Roberta Grossman, with Nancy Spielberg as executive producer, the film takes viewers vividly inside the Ghetto, using rarely seen archive footage and persuasively mounted recreations, to explore the making of the Oyneg Shabes Archive — an illuminating collection of thousands of documents detailing Jewish life in Nazi-occupied Poland, as seen through the eyes of Warsaw natives and some of the tens of thousands of refugees crammed in with them.

Collected clandestinely under the leadership of historian Emanuel Ringelblum, and buried in metal boxes and aluminium milk churns, the trove of eye witness testimonies, memoirs, photographs, poems, stories, jokes, posters, Star of David armbands, essays, cuttings from the underground press, postcards detailing deportations, the first recorded account of the mass murder of Jews by gas in a death camp, and more, is “perhaps the most important collection of original material compiled by Jews during the Holocaust,” says Antony Polonsky, Professor Emeritus of Holocaust Studies at Brandeis University.

However while it was assembled at great risk to the lives of Ringelblum’s group — codenamed Oyneg Shabes (“Joy of the Sabbath”) for secrecy — their remarkable, ingeniously executed act of defiance isn’t as widely known as, say, the Warsaw Ghetto uprising. Grossman herself admits that she only learned about it in 2012, or thereabouts, after coming across a review of Samuel Kassow’s book, Who Will Write Our History?, upon which she based the documentary.

“I’ve been reading about the Holocaust my whole life,” she tells me over the phone during a trip to Paris, “and I thought I knew a fair bit, and I’d never heard of the archive. It just seemed outrageous to me that it wasn’t a more well-known story, and I wanted to see what I could do to change that.”

Much of the archive’s power comes from the urgency and intimacy of people living in extreme circumstances talking about their experiences in their own voices. The Nazis didn’t just want to kill the Jews, but to “erase their memory and control the narrative,” says Grossman. “The people in the Oyneg Shabes Archive were fighting against that, and literally fighting, number one, to be remembered in their own words; and number two, to tell the story of the war from the Jewish point of view.”

Ringelblum (played in the film by Piotr Glowacki, with readings of his work hauntingly voiced by Adrien Brody) sensed when the Germans invaded Poland that a new historical time had begun. He started to keep a diary in which he wrote about the systematic brutalisation of Jews and the removal of their freedoms. Meanwhile, in Warsaw’s cinemas, Nazi propaganda films portrayed Jews as unhygienic and disease-ridden, “trying,” says Grossman, “to convince the Polish population that it’s in their best interest to be segregated from the Jews.”

After the city was split up into areas for Germans, Poles and Jews, and the latter found themselves suddenly and unexpectedly shut off from the Aryan side, the Nazis carried on their campaign of distortion. Film crews and photographers from their propaganda unit were an almost permanent presence inside the Ghetto, shooting people in degrading and dehumanising set ups. Thus when we watch footage from the Warsaw Ghetto today, says a contributor to the documentary, we need to be aware we are seeing life through a Nazi lens.

The Oyneg Shabes members knew what was happening, and all mention the cameras in their diaries, says Grossman.

“Abraham Lewin [a schoolteacher] talks about how his wife was swept up into one of these filming situations where she was forced to stand all day doing something over and over again.

“So they were very aware of propaganda and they were very aware of the point of view of the Nazis and the way they were trying to portray them.”

Grossman’s recreations are a counter to this. Based rigorously on material from the archive and some post-war writing from Rachel Auerbach (one of only three members of the Oyneg Shabes group to survive, and the character Grossman uses as her entry point to the story), they take us into people’s homes and places of work, showing us aspects of Jewish life deliberately ignored by the Nazis.

“We don’t have Jewish photographers and Jewish cinematographers [in the ghetto] . . . so if we were going to visually experience the very personal writing of the archive, it seemed to me there was no other choice but to create these scenes,” explains Grossman, acknowledging that it was a “dangerous decision” because of the “knee-jerk” reaction some people have to dramatisations in documentaries.

The day after the ghetto was closed in 1940, Ringelblum called a meeting of professionals and academics who would form the Oyneg Shabes executive. They were given notebooks, and told to document everything they witnessed. Very soon men, women and children from different social strata were also writing, often without knowing how their work would be used or even being aware of the existence of the archive.

A Socialist Zionist, Ringelblum “was very interested in the common man and the people and the workers, the Yiddish masses,” says Grossman, “so he bent over backwards to make sure the voice of the average person was included.”

At first they just documented day to day life. But as the Final Solution evolved, the mission shifted to documenting atrocities. The archive was always a kind of j’accuse, says Grossman, but “the nature of the accusation became more and more extreme.”

As circumstances worsened, Jewish writers grappled with the effects of hunger and such ethical questions as who should be fed, and what it meant to walk past someone on the street who was dying or already dead. When the Jewish police tried to save their own skins by rounding up fellow Jews during the Great Deportation, they were bitterly denounced. This testimony, written in the heat of the moment, sets the archive apart from most post-war survivor testimony.

It may also explain why the archive didn’t immediately receive the attention it deserved.

According to Kassow and the scholar David Roskies, “it was much too honest,” says Grossman. “It’s not about bad Germans and good Jews. There are some good Germans and there are Jews who are turning in family members to curry favour with the Gestapo.

“There are Jewish prostitutes. There’s the Jewish police that participated so actively in the deportation. So it’s not simple.”

Nor was it meant to be. Ringelblum knew that for the material to be believed by future historians (sadly he, his wife and their young son were executed after being discovered in hiding), each individual story needed to be told from as many different perspectives as possible.

“So perhaps, ultimately, its greatest strength, which is its historical veracity, caused problems right after the war,” suggests Grossman.

Today the timing of the documentary’s appearance couldn’t be better. Since Grossman first conceived the idea of making it, seven years ago, the world has changed in ways that make the message of the Oyneg Shabes and their heroic spiritual resistance not only apt but necessary.

“This is a film about a group of people who are willing, literally, to die for the truth. And now we’re living in an era experiencing a certain rise of fascism, and where people talk about things like ‘truth is not truth’ or ‘alternative facts’, and they’ll attack journalists who are the ultimate truth-tellers.

“The zeitgeist could not be more appropriate, or vice versa. I think the film really speaks to people right now.”

UK screenings of Who Will Write Our History will take place on January 27 at JW3, at the Learning from the Righteous charity in High Barnet, at the Flavel Arts Centre in Dartmouth and in Colchester