There is a moment while watching 1917 when you realise you have not breathed in quite some time, writes George Gaynor

At least it certainly feels that way, such is the relentless, heart-stopping momentum of Sir Sam Mendes’ epic war film about two young soldiers who venture across enemy lines to deliver a message that could save hundreds of lives.

It marks a change in genre for the Oxfordshire film-maker, who has just received a knighthood in the New Year honours and is best known for James Bond movies Skyfall and Spectre and dramas such as American Beauty, Road To Perdition and Revolutionary Road.

“I had this idea of the story my grandfather told me of carrying a message,” says the lifelong film buff, who was educated at Magdalen College School and celebrated his marriage to trumpeter Alison Balsom in Great Tew.

“But the problem of the First World War in general is it’s a war of paralysis.

“It was only when I started researching it that I found this time in 1917 when the Germans retreated, and the land they were fighting over was abandoned. There seemed to be a story possible to tell of this epic journey.”

The film is movingly dedicated to the director’s grandfather, as well as the others who served in the armed forces in the Great War, which brought with it the weight of responsibility of honouring their sacrifice.

“It was not just familial responsibility but also generational,” says the director, who also plays cricket for Oxfordshire Over 50s and once turned out for Shipton-under-Wychwood at Lords in the final of the Village Cricket Cup.

“You have a responsibility, it sounds corny, to the men who fell in the war and the generation that was lost.

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“There aren’t many movies made on this scale that are not franchise movies these days and to be able to be allowed to make one about the First World War, you do feel there is a responsibility to try and get details right and to make something that feels not like a dry history lesson.

“You don’t want it to feel all distant and ‘good for you’ but something that is an experience and that is going to make the war feel vivid and like it happened yesterday.”

A crucial part of the experience of following the journey of the two soldiers, played by George MacKay and Dean-Charles Chapman, is the way the film is made.

It is shot as if in one long take, using clever camera work and editing to create a sense of continual motion.

“I felt it was all part of the same two hours of real time,” Sir Sam, 54, says, “one continuous shot. You can’t get out of it, you have to take every step with these men, whether you like it or not.

“But I was also very conscious that it shouldn’t be repetitive or monotonous or just a headlong race.

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“Because you’re in one shot, you also have to build into it moments of pause and quiet and reflection and lyricism and all these other things so it feels like it’s constantly shifting and moving rather than it just being this incessant headlong dash.”

But filming in such a way was not without its problems, especially when there is so much room for human error.

“You have seven minutes of magic and then if someone trips or a lighter doesn’t work, you have to start again and none of it is usable,” he remembers with a laugh.

“We did see-saw between thinking, ‘Why are we doing this to ourselves?’ and ‘This is the only way to work’.”

But throughout the whole process, he had a crystal clear vision of how he wanted the film to look, meaning he even penned the script himself, alongside screenwriter Krysty Wilson-Cairns.

“I had not been a frustrated screenwriter, I just felt like it would be so much easier if I did it myself,” he says frankly.

“Otherwise I would have to try to explain it to someone else who then had to write it and I would then tell them it was wrong, so it just seemed like I needed to make the journey between what was in my head and what was on screen as short as possible.

“I thought it would be easier if I just sat down and did the work myself for a change, rather than make it the problem of a screenwriter.

“So I did a lot of work and got a story structure but then I sort of stalled and it was Krysty who put it into screenplay form.

“I can’t say I have been sitting there willing myself to write all these years, but having done it, I loved it and I hope I will do it again.”

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But having worked with great playwrights through his distinguished theatre career, he admits he is still “a relative novice” when it comes to writing.

“You certainly become more vulnerable because you have no-one else to blame.

“You can’t say, ‘Well it’s the bloody script’, because that is my fault as well.”

Sir Sam, who was previously married to Titanic star Kate Winslett and actress Rebecca Hall, is aware that his film is an increasingly rare commodity – a big-budget, dramatic epic that is not part of a franchise.

“It is not a sequel, it’s not a franchise, and it’s not an animated film and that is basically 95 per cent of what plays on big screens, or at least on large numbers of big screens, now.

“And I do think it’s important, I think you have a responsibility if you’re a film-maker who is interested in scale, to make a movie that needs to be seen on the big screen.

“I have made movies of all sorts of scale, big franchise movies, but I’ve also made tiny independent films.

“Some of the movies I made I would be fine about being seen on a smaller screen now, because small screens are getting better and television generally is superlative, and so when you do step up and make something for the cinema, you need to make it feel like you’re missing out if you’re not seeing it on the big screen.”

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WHAT OUR REVIEWER THOUGHT....

Practice makes breathlessly choreographed and nail-bitingly tense perfection in Sam Mendes’s real-time thriller, inspired by stories of The Great War told by the director’s grandfather, who served as a lance corporal.

Shot in real-time in several exquisitely staged single takes, which have been seamlessly stitched together by editor Lee Smith into a continuous fluid shot, 1917 is the product of six months of intense rehearsals and preparation, which included a physically gruelling training camp for hundreds of actors including leads Dean-Charles Chapman and George MacKay.

They undertook daily military drills in hobnail boots, acclimatising to the weight of uniforms and weapons before filming began so it would become second nature to check bayonets as hell unfolded around them.

This pre-production period allowed Mendes to work closely with Oscar-winning cinematographer Roger Deakins to meticulously map out the intricate camerawork of each sequence, which places us in the trenches with the characters or pirouettes around impossibly tight spaces as bullets scythe through the air and blood seeps into shifting seas of thick mud.

It’s a tour-de-force of technical daring, which repeatedly dazzles and dumbfounds, juxtaposing heart-breaking brutality and self-sacrifice with moments of dreamy, poetic introspection.

Mendes’s script, co-written by Krysty Wilson-Cairns, oscillates between agonising suspense (a sprint across No Man’s Land littered with the corpses of fallen horses towards the German trenches) and ominous calm (a short journey in the back of a truck crammed with troops).

This is visceral, gut-wrenching film-making that marches us into battle in uncomfortable proximity to the characters, compelling us to hold our breaths for long stretches of the two hours.

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Lance Corporal Tom Blake (Chapman) and Lance Corporal William Schofield (MacKay) begin April 6, 1917 in peaceful slumber against a tree as thunder rumbles in the distance.

The men are roused to receive orders from General Erinmore (Colin Firth), who must prevent Colonel Mackenzie (Benedict Cumberbatch) from leading The 2nd Devons into a trap set by the Germans.

“We would lose two battalions – 1,600 men – your brother among them,” Mackenzie sombrely informs Blake.

The Germans have severed all telephone lines so the only way to warn The 2nd Devons is to dispatch Blake and Schofield on foot into enemy territory to reach Mackenzie before dawn, when the fateful order will be given to attack the line.

1917 unfolds in real-time, pushing actors to the physical limit as we plunge headfirst through the emotional wringer with them, experiencing similar dizzying gut-punches as tragedy stalks their odyssey.

Thomas Newman’s orchestral score possesses the urgency of a ticking pocket watch, underscoring Mendes’s directorial brio and devastating performances from Chapman and MacKay.

Fleeting cameos from the likes of Andrew Scott, Mark Strong and Richard Madden don’t distract from an intimate tale of valour and brotherhood under fire that sears into the memory.

1917 (15) 9/10