I can't breathe...

The scary thing about sarin is it's odourless and colourless. You're not even sure if it's there, but before you know it the gas seeps into your lungs, then your heart. I've put my gas mask on, twisted the valves, just like they trained us at Sandhurst, and still nothing. I desperately try to inhale again but no matter what I do, there's no air.

More rockets whizz past, lighting up the night sky, shaking the earth around me. Then the crackling sound of gunfire fills my ears. If I keep the mask on, I'm going to die. If I take it off, I'm going to die. And if I stand and run then I'm going to get shot in the crossfire.

I see one of our Land Rovers fifty yards away, and suddenly I know what I must do. With my lungs almost empty and my muscles burning, I run...