It was an amazing experience, partially in educating me about how fantastic NATO is at doing its job. During my time there, I interviewed everyone I could, including American soldiers at various camps. As for the Himalayas, I first visited there thirty years ago, and I've returned a dozen times or so. I've led and climbed on expeditions to Everest and Makalu, and that gave me a sense of how real expeditions work. The social contract can get pretty tattered when you're in a pressure cooker at high altitude and in a dangerous environment.
Little details take on enormous magnitude, things like a last candy bar or someone's snoring.
So my experience in the Himalayas helped me paint a realistic picture of how my expedition force might really unravel. While we're on the subject of autobiography, I should confess one thing. While my father, a geologist, used to take my brothers and me into the occasional cave, I am not and never will be a spelunker. In all honesty, the underworld I've conjured up in The Descent comes straight out of my worst nightmares.