A hero broken by war: Afghanistan veteran Jake Wood admits he's a walking timebomb - and there are hundreds more like him

Struggle: Jake Wood spiralled into the bleakness of Post-Traumatic Stress Disorder

Jake Wood is paranoid. To stand any chance of sleep at night, he must lie facing a closed bedroom door with a hammer close to hand under the bed, so he can kill any night intruders before they kill him.

And even then he may well wake up screaming and drenched in a sweat of terror.

Taking a shower in the morning, he never takes his eyes off the bathroom door, though he knows full well that it is locked and bolted.

Out in the street, the sound of a pneumatic drill sends him to the ground on one knee, arm raised, primed to fire.

‘Just the bang of a door and I am back in Afghanistan,’ the former soldier says.

Everyday life defeats a man whose courage under fire cannot be questioned, but who is haunted by what he has seen and done.

‘I cannot stand the sensation of anyone walking unseen behind me. On the Underground, I never take my eyes off anyone with a backpack in case their hands make a sudden movement towards a detonator.’

His senses deceive him. ‘I see blood in the blank canvas of snow, just as I saw blood in the pale sand of Helmand Province.

'I know I am hallucinating, but when I turn away and force myself to look again, it is still there.’

And, as he explains movingly in a new book, Wood knows the precise moment he finally lost control in Afghanistan.

As an experienced Territorial Army NCO, he was trying to stay alive under an enemy onslaught on forward operating base Inkerman — a makeshift outpost behind mud walls in the dangerous Sangin Valley — when a mortar eviscerated his respected, loved company commander.

As the ‘boss’, Captain Dave Hicks, lay dying in front of him in 2007, Wood’s mind went blank and his eyes took on that far-away look known as the ‘thousand-yard stare’ — the indication of a man who’s seen too much blood-letting and done too much killing.

What angers him is that ‘idiots’ back home who know nothing about the reality of war try to emulate that look.

‘I know of young men, sitting in front of war films and war games, who idolise this condition as a mark of a true warrior. But only some naive soul who had never felt this nothingness would think something so dumb.

‘You are no longer human, with all those depths and highs and nuances of emotion of a normal person. There is no feeling any more.

‘My mind has locked all this down. Instead, there is just an overwhelming blackness.

‘But when I close my eyes, I see the faces of the Taliban I killed. And I see Dave Hicks on a stretcher, a gaggle of anxious soldiers around him, an arm holding an IV fluid bag above him, voices urging him to hang on and him shaking gently as he tries to stay in this life, but can’t . . .’

Here is the almost unbridgeable gulf of understanding between the reality experienced by front-line soldiers we send to fight in Afghanistan and ‘home’ — the safe place they leave and then return to, many scarred in a way that the rest of us can barely imagine.

As a military historian, I have read thousands of first-hand accounts of war, in all its gore and glory, brutality and suffering. But there were tears in my eyes as I followed Wood’s story of his descent into the bleakness of Post-Traumatic Stress Disorder (PTSD).

I fear that, having sent tens of thousands of our young men and women to fight in Iraq and Afghanistan, our society sits on a volcano of suppressed emotion like his that — with the condition still not fully grasped and sympathised with — may erupt in our faces in years to come.Wood, a lance-sergeant, was a part-time soldier, dropping in and out of three-month and six-month tours.

It made the contrast with ‘normal’ life even sharper and more painful.

One minute he was just another grey-suited systems analyst in a bank in the rat race of London’s financial district, fighting for a place on the Tube or a drink at a bar.

The next, he was a squaddie in sand-coloured fatigues, toting an SA89 assault rifle in the badlands of Helmand Province, being shot at by Taliban insurgents.

The dissonance was huge and mind-blowing. He chose to go to war. He was bored at work, he had girl trouble, he wanted some excitement.

So, as a fully-trained member of the Honourable Artillery Company, the City of London’s centuries-old volunteer regiment, he went to Iraq in 2003 with the invasion force to oust Saddam Hussein.

Out on patrol, he lapped up the danger and thrived on the camaraderie.

Then, back home in the office, he was among people he could no longer relate to, living lives he thought frivolous. He felt like an outsider.

At the next opportunity, he took leave from his job again and returned to Basra in Iraq, where the British occupation force was fighting an increasingly bloody war against the insurgents armed with deadly roadside bombs and rocket- propelled grenades.

Under siege in their fortified camps, he and his mates endured ‘bowel-turning, sweating wet eternities of terror’.

Out on patrol, each man faced the extra horror of knowing that capture could well mean being beheaded.