You’re not alone if you don’t know much—or anything, for that matter—about the Peterloo Massacre of August 16th, 1819, when a confrontation between protestors in Manchester, England and the British cavalry turned violent. Peasants and tradespeople descended on a Manchester square to air their grievances, only to be met with armed resistance that resulted in well over a dozen deaths and hundreds of injuries.

Filmmaker Mike Leigh, director of the new film “Peterloo,” says the event is little-known, even in the U.K.

“You can get on the bus by the house where I lived as a kid and get to where it happened in fifteen, twenty minutes [but] I never knew it about it,” Leigh said during a recent stop in Washington, D.C., to promote the film. “Don’t ask me why, because it is quite a famous and important event.

“That’s one of the reasons to make the film. I think it’s about time we alerted people to it.”

“Peterloo” runs over two and a half hours and features no central character, with the ‘massacre’ taking up only the last part of the runtime. It was important, according to Leigh, to paint a nuanced picture of British society at the beginning of the nineteenth century, with the Napoleonic wars astern and the kingdom having so recently lost possession of its colonies across the Atlantic.

“In the late seventies or early eighties, I read a book about it […] and I remember thinking, someone ought to do a movie about this. I didn’t think at that time that that somebody would be me.”

There is no true main character in “Peterloo,” with Leigh’s screenplay bouncing back and forth from among the various strata of British society at that time. Simply recreating the violent event itself, without building up to it with his snapshot of British life at the time, would have been “meaningless,” he added.

“You have to be invested in knowing who all these people are, so when you get to the Peterloo day, you understand what’s going on. It was never an issue not having a central character. That’s not what this film is about and not what it demands.”

“My philosophy is, I want to bring down the fourth wall so the audience absolutely gets into what is happening and what happens next.”

While Leigh’s films are nearly all expressly about modern British life, he has in fact fashioned other period pieces, such as “Topsy-Turvy” (1999), about the powerhouse musical duo Gilbert and Sullivan, and “Mr. Turner” from 2014, with Timothy Spall as the painter. Leigh famously begins with a story outline only, then hires actors and, through the rehearsal process, creates the script with them collaboratively.

“With ‘Topsy-Turvy’ and ‘Mr. Turner’ and this film, you absorb the history,” Leigh said. “It’s about dramatizing events. And the script is something we arrive at through finally being on location, and improvising scene by scene, and scripting it with the actors.

“But that’s always, and this one is no exception, preceded by a measure of preparing with the actors and working on the characters and research.”

Leigh’s famously worked outside the studio system for decades. Although he has been nominated for an Oscar six times, his films have sometimes had trouble finding their way beyond cinephiles. But if that is the price of having autonomy over his projects, Mike Leigh is willing to pay up.

“I’ve had a very simple principle, that, I’ve walked away from any project that looks like it’s going to be interfered with, and that’s been a lot of occasions,” he said. “Amazon Studios has been wonderful. They never interfered at all,” he said of “Peterloo”’s distributor.”

Leigh and his longtime lensman, Dick Pope, were fans of celluloid, but digital film has allowed them to open up the possibilities, such as increasingly long takes and crisper images.

“Technology is a tool that allows you to do extraordinary things,” Leigh said. “From my point of view, that doesn’t really [interfere] with what I’m really concerned with, which is to put people on the screen. People are people [no matter] what tool you use to capture them.”

August 16th will mark two centuries since the Peterloo massacre, which made the film timely from an anniversary perspective. But more than that, Leigh believes his movie’s exploration of the divide between the haves and have-nots, as well as the importance of fighting for rights against sometimes-oppressive forces, is relevant to audiences today, still.

“Tragically, there’s a family of such events. Tiananmen Square or Charlottesville, you name it,” he said.

As far as what he wants audiences to take away from “Peterloo,” Leigh is loath to reductionisms about lessons and of dictating to filmgoers “think this.”

“I very deliberately take you to a place and leave you where you can be sad, upset, angry and then discuss and medicate and argue and wonder how it might otherwise have been,” he said. “It’s [not just] a film about democracy.

“The point of this film, more than anything else, is [as] you’re watching the various scenes on the road to the big event, you know that something terrible is going to happen,” Leigh said. “However little you may have in the way of historical background, you still know that is lurking.”

“Peterloo” is playing now