History suggests that the constant drip of unfettered, prime-time images depicting death and defeat made a vital contribution to turning the tide of American popular opinion against the war in Vietnam. It’s hard to imagine a similar decisive impact in the era of multi-channel, 24 hour rolling news. Does the latest British fatality in Afghanistan now provoke more than a tinge of sadness, a fleeting moment of compassion?

Photographer turned award-winning filmmaker Danfung Dennis is convinced that the media should play a crucial part in shaping our understanding of global conflict and its human casualties.

‘I think we need to use technology to challenge the boundaries of traditional storytelling and create more immersive experiences,’ he argues. ‘That’s one of the reasons I’ve moved from the still image to the moving image. We often see a very sanitised image of war. It doesn’t convey a sense of what it is actually like to be there. I want to show the emotion and the devastation of what it means to be at war.’

Dennis’ first feature film, Hell And Back Again, views the American presence in Afghanistan through the experiences of Marine Sergeant Nathan Harris as he serves on the frontline and returns home to deal with the consequences of a crippling injury. It combines the emotion of a drama with the authenticity of reportage and won both the Grand Jury and Cinematography prizes at this year’s Sundance Film Festival.

‘I had no intention of making a film when I went to Afghanistan,’ Dennis explains from his base in New York. ‘I just wanted to try and convey what was happening there as honestly and truthfully as I could.’

Dennis, 29, is an experienced photojournalist whose images of the conflicts in Iraq and Afghanistan have appeared in Newsweek, The Guardian, The Washington Post and countless other publications. He was an accredited journalist with the New York Times when he joined the marines of Echo Company in July 2009 as they embarked on a major offensive in Southern Helmand. Armed with the pioneering handheld Canon 5D Mark II still camera, and able to record 12-minute segments of high-definition video, he became a one-man film crew able to capture anything from the epic to the intimate.

‘I asked to go with the company that was being dropped the farthest behind enemy lines,’ he recalls. ‘On the first day, one marine died, 12 had collapsed with heat exhaustion and we had all run out of water, including me. Nathan Harris gave me his last bottle of water and from there I followed him. I came to trust him and he came to trust me.’

Six months later, when Echo Company returned from their tour of duty, Harris was nowhere to be seen. Dennis discovered that he had been shot through the hip and leg and was facing a long, painful spell of hospitalisation and rehabilitation. He was invited to the Harris home in North Carolina and introduced to his wife Ashley.

‘I was accepted into this small, rural Baptist community. I essentially lived with Nathan and his wife as he readjusted and transitioned into society. He knew that I understood what he had been through. I had captured him being this perfect warrior and leading his men so he was very open to showing the rest of what it means to be a warrior; to come home from war and face these psychological and physical injuries.”

The real value of Hell And Back Again lies in the contrasts between the battle zone and a home front where Harris has no obvious connection with other people and no appetite for the daily complexities of paying bills, making choices and living a ‘normal’ life. As he faces an addiction to painkillers and displays a disturbing fondness for firearms, the film starts to carry echoes of landmark 1970s movies like Taxi Driver or The Deerhunter.

‘I have borrowed from the world of narrative cinema,’ Dennis readily concedes. ‘I’ve used a lot of cinematography techniques to try and capture the visual language of narrative film but also the narrative arc and the powerful emotional impact that usually comes with a narrative film. People almost forget that they are watching a documentary. When they do realise that it is real it hits them that much harder.’

True to his ambition of pushing the boundaries of documentary, Dennis is now a founder of Condition One, a mobile media technology company with big plans for the future.

‘Condition One is an evolution from what I have been doing as a journalist and filmmaker,’ he explains. ‘I’m trying to create these highly visceral, emotional and immersive experiences to better convey these indescribable experiences that we usually just see in a frame or on a piece of paper. What I am trying to create now is much more honest, truthful representations of these experiences to actually allow people to be there and experience it first hand.’ The reporting of modern warfare might never be the same again.

Hell And Back screens with Blood And Dust, George Square Theatre, Sun 26 Jun, 4pm.

Hell and Back Again exclusive clip 1