On the weekend of “Run All Night” comes “ ’71,” which is also about one long and treacherous night in the life of a man desperately trying to survive while being pursued by Irish gunmen with the worst of intentions.

The similarities pretty much end there.

In one of the more impressive feature directing debuts in recent years, Yann Demange has fashioned a searing, remarkably realistic and unforgettable period piece thriller reminiscent of the docu-drama films of the great Paul Greengrass (“Captain Phillips,” “United 93,” “Bloody Sunday.”)

Jack O’Connell, who spent most of Angelina Jolie’s World War II film “Unbroken” enduring unspeakable tortures at the hands of a sadistic Japanese POW camp commander, is once again playing a soldier who’s banged up and battered to within an inch of his life — but this time it all happens over the course of one long and extremely harrowing night behind enemy lines during the Troubles in Northern Ireland in 1971.

Just 25 and looking younger, O’Connell gives a stirring performance as Gary Hook, a green recruit with the British Army who is deployed to Belfast even though he and his mates are clearly far too inexperienced to navigate the tricky politics, the shifting motives of agents and double agents, and the increasingly agitated locals who greet their presence by throwing bags of feces and rocks at them.

Once shots are fired and blood is spilled, the parallels between Northern Ireland in the early 1970s and the Iraqs and Afghanistans of current day are clear without any heavy-handed symbolism from Demange and screenwriter Gregory Burke. It’s chaos in the streets, with the British soldiers doing everything they can to not fire — until an Irish civilian shoots a Brit in the head, execution style, and a full-scale riot ensues.

Gary barely escapes with his life, but his unit leaves him behind, either unwilling or unable to get to him. (It’s possible they believe he, too, is dead.)

From that point on, the complex, sometimes convoluted nature of the conflict is reflected in Gary’s experiences. A young Irish boy comes to his aid. Members of the Provisional IRA construct a bomb in the back of a pub while Gary sits out front, awaiting his fate. An Irish couple find Gary near death, passed out on the street, and they debate whether to come to his aid or to keep on walking — because helping this man will put their own lives in imminent danger.

O’Connell is brilliant at conveying Gary’s resourcefulness and bravery — but also the flat-out terror he feels when he’s certain his life is about to end. This young man is no hero. He spends little or no time trying to understand the politics that put him in a uniform and led to strangers either wanting to cut him to pieces or risk their lives to save his. He just wants to go home.

“ ’71” is filmed with such a realistic tone, at times it was a little difficult to follow what was happening in the nighttime fog of war. Once or twice, I found it hard to decipher the thick British and Irish accents. And Demange didn’t do himself any favors by casting two main characters — one Irish, one British — who look alike, down to the facial hair. It just added to the mild confusion.

Quibbles. Frame by frame, “ ’71” is one of those intense war thrillers where you know it’s fiction, you know it’s not a documentary, and yet every performance and every conflict feels true to the history and the events of the time.

[s3r star=3.5/4]

Roadside Attractions presents a film directed by Yann Demange and written by Gregory Burke. Running time: 99 minutes. Rated R (for strong violence, disturbing images, and language throughout). Opening Friday at local theaters.