The 13,000 Jews who fought to the death in the Warsaw Ghetto Uprising are celebrated 75 years later as heroes who refused to surrender to the overwhelming firepower of the Nazis.

But another group of Jews in Warsaw also carried on a heroic struggle, without guns or Molotov cocktails. Using pens, typewriters and paper as their weapons, they secretly chronicled life in the ghetto — and those hidden memories became the basis for much of what we now know about life within the ghetto’s walls.

The 60-member group, led by historian Emanuel Ringelblum, met on Saturday mornings and called itself “Oyneg Shabes,” Yiddish for “Joys of the Sabbath,” to hide its true intent.

Members collected more than 35,000 pages of diaries, letters, photos and newspapers, as well as items such as food ration cards and Nazi-mandated armbands, burying them in metal boxes and milk cans — many of which were recovered after the war.

Oyneg Shabes members were determined to tell the world what life was really like in the ghetto, and not to allow Nazi propaganda films — which depicted the Jews as dirty carriers of lice and typhus — to tell their story. And when they became aware of the mass murder of Jews in concentration camps, the group also took on the role of telling the world the horrific truth of the Holocaust.

Ringelblum and his group are the subjects of “Who Will Write Our History,” which will make its world premiere July 21 at the San Francisco Jewish Film Festival. It is based on the similarly titled 2007 book by Samuel Kassow.

The 94-minute film, which includes footage from the ghetto and narration based on the writings of those who contributed to the archive, as well as reenactments by professional actors, includes the final thoughts and prayers of people who knew they were doomed.

“We hope to extend what Ringelblum set out to do, which is to let the Jewish people incarcerated in the ghetto and ultimately murdered in Treblinka speak for themselves,” said Roberta Grossman, the film’s director and founding partner of Katahdin Productions, an L.A.- and Berkeley-based nonprofit documentary production company that produced this film as well as her previous films, including “Above and Beyond (The Birth of the Israeli Air Force)” and “Hava Nagila (The Movie).”

“It was also a way for people to make some sense of what their experiences were, and to make some meaning of their suffering,” said Grossman, who received her bachelor’s degree from UC Berkeley.

The executive producer was Nancy Spielberg, who told J. that her understanding of the Holocaust only really began when her filmmaker brother, Steven Spielberg, made “Schindler’s List.” She said the members of Oyneg Shabes, like Oskar Schindler, were instrumental in preventing the Nazis from eradicating the Jewish legacy in Poland.

“In their action of writing, it was winning in some ways,” she said. “It really was being able to assert themselves and to not let the Nazis win.”

Grossman said her film is more relevant today because of the battle between truth and propaganda going on now in many parts of the world. That makes “the issue of who tells the story” crucial, she said.

Dorota Liliental, a Polish actress who plays the role of a soup kitchen worker in the dramatized portions of the movie, said the archive and the film are important because they tell the story from the perspective of those who suffered.

“I’m really, really happy this film was made,” Liliental, who got a degree in theater from UC Berkeley in 1988, said in an interview at the Polin Museum of the History of Polish Jews in Warsaw. “History usually is written by those who survive and those who win, and their vision might be distorted. And here we have history written by the dead.”

Along with stories of heroism and self-sacrifice, the archive tells of everyday life for the half-million Jews crammed into the ghetto and dealing with hunger, disease and Nazi brutality. Grossman said she realizes many viewers glaze over when they encounter “another film about the Holocaust,” but said Ringelblum’s story is unique.

“I believe this is the most important unknown story of the Holocaust. There is nothing that compares to the Oyneg Shabes,” she said. “Ringelblum made sure there were all different perspectives, so there are stories about brutal Jewish police and Jewish prostitutes and people who turned in family members for small favors from the Gestapo.”

Grossman made several trips to Warsaw to read through the archive in the basement of the Jewish Historical Institute, where the diaries and other documents were kept until a permanent exhibit opened there last November. That exhibit includes some of the original pages, as well as one of the milk cans stashed beneath the basement of a school.

The movie is told from the perspective of Rachel Auerbach, one of only three members of Oyneg Shabes to survive the Holocaust. She spent years leading the effort to search for the archive, parts of which were unearthed in 1946 and in 1950.

Auerbach, a journalist who went on to oversee witness testimony at Israel’s Yad Vashem from 1954 to 1968, was assigned by Ringelblum — who led the Jewish social service agency in the ghetto — to run a soup kitchen. Her observations of the starving Jews who came there for food became the basis of much of her writing, in Polish and Yiddish.

Among the writings on display at the JHI is the last will of one of the four people who buried the archive in 1942.

“I don’t know what fate awaits me. I don’t know if I’ll be able to tell you what happened next. Remember: my name is Nachum Grzywacz,” he wrote.

“Who Will Write Our History,” 6:15 p.m. July 21 at CineArts, Palo Alto; 4 p.m. July 22 at the Castro, S.F.; and 6 p.m. July 28 at the Albany Twin.