Oscar Isaac and Charlotte Le Bon star as Armenians living in the last days of the Ottoman Empire. (Open Road Films)

Sometimes the facts are the most important parts of a work of fiction.

“The Promise,” out tomorrow, is a love story between Mikael (Oscar Isaac) and Ana (Charlotte Le Bon), both Armenians in the Ottoman Empire (now Turkey) during its last days. As World War I erupts, the Turkish government turns on its citizens of Armenian descent, eventually killing more than a million of them in executions, forced labor and death marches.

The official position of the Turkish government is that what a majority of historians call the Armenian genocide never happened — that the deaths were merely collateral damage from the war, not targeted murders. That made it tricky for director and co-writer Terry George. Luckily, he’d been through similar situations before.

“On ‘In the Name of the Father,’ the British press attacked it for two reasons,” he says, referring to the script he co-wrote for the fact-based 1993 film about the British imprisonment of a group of people falsely implicated in an IRA bombing in the 1970s. “They said [prisoner] Gerry Conlon wasn’t in the same cell as his father, which he wasn’t — he was in the cell next to him, but that’s hard to shoot. The other was, at the end in the court, the judge says, ‘Can you approach the bench?’ and they don’t say that in British court. So those two items became the basis on which the film was attacked.”

For “The Promise,” fact thus became an integral part of fiction. “I was extremely fastidious on the real political moments that the story tells. All these historical moments, I can cite several historians,” he says. “I’ve learned to catalogue and very carefully research all those [real] events. I’ve learned that those little things are very important.”

Sometimes, though, it’s not the little things — just the simple fact that “The Promise” says that the Armenian genocide happened has turned into a very big thing. Users of an online Turkish message board have launched an online campaign to tank the movie’s ratings, according to The Hollywood Reporter. Since the movie debuted at the Toronto Film Festival last year, the film has received more than 120,000 ratings on IMDb — and over 61,000 of them are one-star.

George shrugs off the controversy, seeming more irritated at “The Ottoman Lieutenant,” a short-run movie released earlier this year about an American nurse and an Ottoman officer during WWI that was more sympathetic to the Turkish side. (“They even used our font on the poster!”) But he’s confident his film contains more truth than that one, even if his plot is largely fictional.

“It’s a distillation of history; you’re boiling down the emotions and the events,” he says. “Don’t create an event that you pretend to be real; that will distort the overall argument of the film.” And the argument of “The Promise” is simple: The story may be fictional, but the history is fact. kristen page-kirby (express)