Christopher Nolan’s dramatic, action-fuelled and emotionally harrowing Dunkirk opens as hundreds of thousands of British and Allied troops are surrounded by enemy forces. Trapped on the beach with their backs to the sea, they face an impossible situation as the enemy closes in. RAF Spitfires try to protect them from above, while hundreds of small boats manned by both military and civilians mount a desperate rescue effort, entering the danger zone to try save individual soldiers.

The film boasts an incredible cast, including Tom Hardy, Mark Rylance, Kenneth Branagh, our own Barry Keoghan (Love/Hate), and Nolan’s frequent collaborator, Cillian Murphy.

Murphy, who is now 41, was drawn to the project as he believes it’s an important addition to the canon of war films, and as it’s helmed by an English director, it offers a unique and much-needed perspective on such a monumental historical event.

“What first struck me about Dunkirk was that it wasn’t an American war movie,” muses Murphy, “which so many of the great movies about war have been. If you were making a list of great modern war movies, I can’t think of a British film over the last 30 or 40 years that you would necessarily place on it. So, I think it appealed to Chris as a filmmaker because he recognised something in the story that was hugely unique, and that audiences wouldn’t necessarily have seen before.”

The Cork native reveals he knew little about Dunkirk, and through his research came to understand not just the political relevance of the event, but the cultural and emotional impact it had on Britain.

“Ireland was a neutral country during World War II,” says Murphy, “so my understanding was quite limited until I learned more about it through research. Dunkirk was an incredible moment in World War II, and in British history as a whole. It was the result of a wartime offensive that went terribly wrong, leaving hundreds of thousands of soldiers stranded on the coast of France. But it was redeemed by the will and determination of the people to bring these boys home. That’s the ‘Miracle at Dunkirk.’ The scope of this immense evacuation, under extreme duress and despite impossible odds, speaks to both the unity of a nation, and the sacrifice and heroism of individual soldiers and civilians. They came together, and were ultimately able to snatch victory from the jaws of defeat.”

Murphy plays a man known only as the Shivering Soldier, a shell-shocked figure picked up by a civilian boat, who has no intention of returning to the hell he’s just barely escaped.

“I think my character is representative of something experienced by thousands and thousands of soldiers,” reflects Murphy, “which is the profound emotional and psychological toll that war can have on the individual. We first meet him when he is picked up by the Moonstone, which is one of the civilian ships crossing the English Channel to evacuate soldiers at Dunkirk. He’s someone who has survived an experience that is mind-alteringly horrific, only to be told, ‘Actually, we’re just heading back into it.’”

A hallmark of Nolan’s films is his preference for capturing the action in-camera and eschewing digital effects and CGI as much as possible. Adding to the verisimilitude, the filmmakers, cast and crew filmed a portion of Dunkirk on the actual beach and at the exact same time of year that the miraculous evacuation happened. Murphy’s scenes were even shot out on the water aboard the actual ship, the Moonstone. The actor has worked with Nolan on four other films – Inception, Batman Begins, The Dark Knight and The Dark Knight Rises – and appreciates his commitment to authenticity, finding that it elevates his own performance.

“When you’re in the environment and things are happening for real, it leads to a more honest, truthful portrayal of your character’s journey,” says Murphy. “I think Chris’s determination to capture as much of the action in-camera as possible is why his films have such an intense and visceral quality to them. On Inception, I remember shooting on the side of a mountain in a snowstorm, and Chris continued to shoot even when it became absolute white-out conditions. If you want to get the most authentic reactions, or the most truthful responses from actors, throw ’em into the real sea or fly real Spitfire airplanes over them. The audience will feel the reality of that – the actors certainly do.”

At such a divisive time, many people may prefer to go to the cinema for escapism rather than gritty and devastating war films, but Murphy believes that the bravery, perseverance and unity portrayed in the film will prove inspiring.

“I hope the film takes people on an exciting, visceral journey,” he says, “but that they’re ultimately moved by the human story that anchors it all. At its heart, it’s a film about courage and survival and the triumph of the human spirit, really. That might sound trite, but I think in this case it actually applies. That is what the real Dunkirk evacuation represents, and I think that spirit is present in every frame of the film.”

Dunkirk is in cinemas from July 21.