IN March, 2009, Aaron Black and James Forrester, young soldiers in the Black Watch, boarded an RAF Tristar transport plane headed for Kandahar Airfield, a hub of the coalition war effort in southern Afghanistan. It was dark by the time word came down for the men to don their body armour for the final approach – a stomach-jolting dive to minimise the risk of being shot down. As they stepped onto the tarmac, the two friends knew they were crossing a threshold: they were going to war for the first time, and they could hardly wait.

Aaron and James were soon fighting shoulder-to-shoulder in Britain’s bloodiest summer of the war. On the morning of June 11, they witnessed the death of their friend, Robert McLaren, a 20-year-old private from the Isle of Mull, who was killed instantly by a massive buried bomb. Aaron narrowly avoided a similar fate when he was later blown through a doorway. Renowned for his dark sense of humour, he would sometimes joke about his close call with James, who would respond with an oft-rehearsed eye roll.

When the Black Watch returned to their base at Fort George near Inverness, the pair lost no time in hitting the Inver Ink Tattoo parlour and the Love2Love nightclub, where they sprayed champagne like racing drivers. At Johnny Foxes pub, Aaron raised a glass and spoke for them both when he said: “This novelty’s never going to wear off. I’m going to feel like this forever.”

The novelty didn’t last. Despite being praised for his “well-controlled aggression” in combat, Aaron began running into trouble with superiors at Fort George and spent much of his savings on drink. A year after returning from Afghanistan, he confided something of his desperation in a text to his older sister: “I feel like I’m losing it Jenna. I need someone to help me,” he wrote. “My head’s a mess … Ever since I got back from Afghan, I was happy for a month or two, then I just dropped.”

Aaron left the Army in May, 2011 and returned to his home town of Blairgowrie, where he slept on his mother June Black’s sofa and began looking for a job. Still drinking heavily, he was arrested over a pub fight. Aaron, whose commander had described him as one of the best soldiers in his platoon, struggled to cope with everyday tasks like fixing a broken washing machine when he began living alone in a council bungalow.

“Trying to work out how to function as a civvie,” he posted on Facebook. “Harder than I thought.”

Soon after he appeared in court, June was woken by police knocking at her door. It was a bitter Friday night in mid-December and she assumed her son must have been in another fight. The police asked if they could come inside. Aaron had been found hanged from the loft hatch of his new flat. An overflowing ashtray lay on the counter, next to a crowd of empty bottles of Stella Artois. Dirty water was still pooled in his washing machine. He had laid out his medals next to his remaining pre-Christmas money: 32 pence, in coppers. He was 22.

The police told June to check her phone. Aaron had sent a text message shortly before midnight that said: “Goodbye XXX.”

“I thought he was a man, a soldier, he could handle anything life could throw at him,” June told me. “I was wrong. He was a strong-minded laddie – I never knew how fragile he was.”

Ever since my first conversation with June, I had been haunted by Aaron’s story. His experiences and June’s fight for answers are explored in-depth in Aftershock: The Untold Story Of Surviving Peace, my new book about the post-conflict experiences of British soldiers. While many who serve in the military later thrive as civilians, there have always been a significant number who struggle, and those who leave the Army after a few years of service are especially vulnerable. Like June, I wanted to know how we could have allowed a popular young man to risk his life in Afghanistan, only to fall in a battle with his own mind. And I wanted to know how we might prevent such tragedies in future.

For two years I travelled around Britain, speaking to ex-forces who had deployed to Iraq or Afghanistan, as well as members of an older generation who had served in the Falklands, Northern Ireland or other campaigns. And I met a hidden Army of wives, partners and mothers – Britain’s true conscripts.

Time and again I was drawn back to Scotland. It was here that I found some of the most poignant examples of personnel falling through the gaps. But it was also where I encountered some of the most inspiring work being done anywhere in Britain to help veterans suffering from post-traumatic stress disorder (PTSD) and other mental health problems, not merely to cope, but to live life in a higher octave. While there may only be relatively small numbers of soldiers who bear invisible wounds from combat, there are new treatments that can make a big difference – provided they are available. With a little imagination, I believe lessons learned in Scotland could provide a model for other countries struggling with a problem as old as war itself.

It has been a century since the physician Dr Charles S Myers introduced the term "shell shock" into the medical literature with a 1915 article in the Lancet describing the trembling and panic suffered by a soldier who survived a barrage of German shells at the outset of the First World War. Like Aaron, the man was a 20-year-old private experiencing his first taste of the front-line. Myers identified him as “Case One” and soon doctors were faced with tens of thousands of emotionally shattered soldiers. Among those doctors was Dr William HR Rivers, who famously treated the war poet Siegfried Sassoon at Craiglockhart outside Edinburgh. Conscripts could rarely expect such individual attention, and many were locked in crumbling Victorian asylums under the label "service lunatic".

Attitudes have come a long way since the days of the trenches, when more than 300 soldiers were shot for desertion. As fighting intensified in Afghanistan, the Army launched a “Don’t Bottle It Up” campaign to challenge the widespread stigma that stops many personnel seeking help. It has also expanded a system called Trauma Risk Management, or TriM, in which soldiers are trained to spot colleagues in distress. Nevertheless, misunderstandings about psychological injury linger. When Aaron took his life on December 16, 2011, James Forrester was serving a second tour. He said a senior non-commissioned officer in the Black Watch had assembled three platoons for a talk some weeks after his friend’s death.

“He called everybody over and gave a brief of how PTSD doesn't exist, and you can overcome it with sheer willpower,” James told me when we met in Kirkcaldy. “I was standing there and I was thinking I wanted to go and punch him right in the face. I was going to say: 'So you're telling me after all the years of trying to break down the stigma, you've just reinforced it one sentence?’”

Unlike the majority of soldiers who choose to keep their problems to themselves for fear of being seen as weak, Aaron did confide in mental health staff that he battled suicidal thoughts and had taken overdoses. A military psychiatrist recognised he was suffering from trauma symptoms. “I have reassured him that we would be able to complete whatever treatment we start,” the psychiatrist wrote in Aaron’s notes.

The therapy never happened. Shortly before leaving the Army, Aaron told mental health staff he was feeling better, but would appreciate some continued support after exit. “Aaron had an expectation of being followed up,” June said. “It never came.”

When personnel leave, responsibility for their healthcare reverts to the NHS, but ex-forces who present with trauma symptoms sometimes find it hard to access effective therapy. Among them was James Lindsay, a strapping machine-gunner in the Royal Scots Borderers, who served alongside Aaron and James Forrester in Afghanistan and who was also present when McLaren was killed.

Lindsay left the Army bearing an “exemplary” leaver’s certificate that paid tribute to his courage and enthusiasm. But the Army had not left him: he would walk his Lochside neighbourhood in Dumfries with the vigilance of a soldier on patrol. His mother, Nicola Howat, would be woken by screams of “Get off! Get off!” as he grappled with Taliban captors in his sleep. Some people seemed to think Afghanistan had been a holiday.

“Even I was asked a couple of times by some idiots: ‘Is that your son home now? How many people did he kill then?’” Nicola said.

Lindsay started sessions with an NHS therapist but soon quit, saying anti-depressants had made him feel disoriented. In January, 2012, he started a temporary job cleaning stairwells organised through a Dumfries charity called the First Base Agency, but his despair was deepening. He was found hanged a week later – a month after Aaron had died. He was also 22. The MoD declined to comment on either case.

Mindful of the struggles faced by such men, the military, charities and the Government have played an increasingly pro-active role in trying to ensure the country’s 400,000 veterans receive the right support. Last year, Eric Fraser, a 37-year veteran of the Royal Navy, was appointed Scottish Veterans Commissioner to oversee provision. The Scottish Government and NHS are also rolling out an innovative service called Veterans First Point, providing drop-in centres to serve as a one-stop shops for ex-forces struggling with civilian life, run by peer support workers who have also served. Combat Stress, Britain’s biggest military mental health charity, also offers six-week doses of in-patient trauma therapy at Hollybush House in Ayrshire, and many other charities provide a wide range of support to ease practical aspects of the transition. The biggest challenge is often finding ways to ensure the help reaches those who need it most. Trained to be self-reliant, soldiers are often reluctant to put up their hands. Those suffering from PTSD may be even less likely to reach out because avoidance and withdrawal are common symptoms.

Even for those who do open up, finding effective treatment is not always easy. The MoD, NHS and Combat Stress often offer people with PTSD a trauma-focused variant of Cognitive Behavioural Therapy (CBT), a long established form of talking therapy in which a therapist helps a client improve their mood by challenging negative patterns of thought. The approach can work for milder cases, but some psychiatrists in Scotland say there is little evidence that CBT is of much use for people who have suffered repeated traumas against a backdrop of severe day-to-day stress – a typical presentation among veterans.

In some cases, a technique called Eye Movement Reprocessing and Densensitisation and Reprocessing (EMDR), in which a therapist uses a wagging finger or flashing lights to stimulate bilateral movement of the eyes, can be more effective. The approach seems to influence deeper layers of the brain than talking therapy and has been used by military and NHS clinicians with remarkable results. Nevertheless, some clients still find the task of confronting their worst memories is too overwhelming.

To offer hope in such cases, Dr Alastair Hull, one of Britain’s leading PTSD specialists, and his colleague Dr Michelle Ramage at NHS Tayside, are pioneering even more advanced techniques at a Veterans First Point clinic that opened in Dundee this month. They include a wide range of breathing and visualisation exercises designed by experts in the United States to help clients achieve the kind of well-grounded sense of calm they need to safely release the emotional residue of their worst ordeals and restore a sense of connection with loved ones.

“Individuals suffering from severe trauma, many of whom are veterans, may be written off and labelled ‘untreatable,’” says Hull. “But we cannot and should not neglect people just because they are suffering the worst symptoms. It’s time to support clinicians to acquire the kinds of skills needed to treat those most in need of help.”

Among Hull’s success stories was a former Special Forces soldier, who I will call Steve, who had spent years in a futile quest for effective treatment before reaching his consulting room.

“Because of Alastair, I don’t have to look over my shoulder every step of the way,” Steve said. “I don’t need to walk into a room and the first thing I do is look for a weapon.”

Others are working on similar lines. In May, psychotherapists Dawn Harris and Colin Howard opened the Centre for Trauma, an in-patient clinic outside Stirling, offering bespoke care to private clients and NHS referrals. In my travels across Britain, I never found anywhere like it – a place where cutting-edge techniques can be used for as long as necessary to help trauma survivors, military or civilian, to truly heal.

With Government backing, the clinic could serve as a template for better trauma services across Scotland and beyond. We might then be able to offer a genuine shot at recovery to ex-forces who share the trauma symptoms suffered by Aaron Black and James Lindsay – a promise that, for all the progress thus far, we are not always able to keep.

Aftershock: The Untold Story Of Surviving Peace, is published Portobello, £20, and is available from October 1

Matthew Green will be talking about the subjects raised in this essay, and the book, at the Wigtown Book festival this afternoon at 1.30pm in the County Buildings, Main Hall, Wigtown www.wigtownbookfestival.com. Green will also appear in association with the Scottish Mental Health Arts & Film Festival at the Dundee Literary Festival www.literarydundee.co.uk on Friday, October, 23 4-5pm, Bonar Hall, University of Dundee

For more on Aftershock visit www.matthewgreenjournalism.com