My college professor was the person who recruited me, doubtless deciding that any sober young man who permanently wore a jacket to lectures complete with leather elbow patches, handed in high-quality assignments on time and appeared to have few friends or social distractions, had to have the Stars and Stripes tattooed on his heart. His respected and flattering opinion – and mostly in my life I believe I have been a person compliant with what I thought of as higher authority – combined with the absence of an alternative salary-earning career meant I went along with it. There were times during the period of training when my assessors didn’t share his confidence and, after one of their many psychological profiles revealed my moral ambiguity about actually having to kill someone, they took their foot off the gas and designated me as a desk jockey with the same sort of disdain that I saw in the Nung guards’ eyes.

By the time I got posted to Saigon, most other Americans had gone home. Nixon’s process of Vietnamising the war had seen the removal of ground troops, collapsing a sizeable proportion of the rampant economy that had blossomed to indulge their every need. Now, mostly, the bars and hotels were frequented by private contractors, the engineers and specialists needed to service the remaining mechanics of conflict and the still-burgeoning army of bureaucrats and intelligence people who were supposed to bring the conflict, if not to victory, then to a satisfactory face-saving conclusion. It would be easy and better to say I never believed in the war but a naive part of me, initially at least, bought into that traditional view that we were building a wall against something that otherwise was going to keep on rolling until it reached our own shore – was intending to flatten our world with the same intensity of a tornado I once experienced as a child. So I was to be a small part of stopping that invasion. I guess too I had been stirred by JFK’s words: ‘Let every nation know, whether it wishes us well or ill, that we shall pay any price, bear any burden, meet any hardship, support any friend, oppose any foe, in order to assure the survival and success of liberty.’

The idealism of these words had been gradually eroded when the reality of the price needing to be paid rendered itself inescapably visible with every flag-draped coffin shouldered across airport runways. And after the revelations about the My Lai massacre it was difficult to persist with any genuinely unsullied sense of moral imperative, so some things had to be compartmentalised and held at a distance from personal conscience, however dishonest and indeed culpable this sounds. It’s what happens when your nation goes to war and you serve part of it, even if your status is never much higher than all the other grunts and your hand never actually fires a weapon. But it was still a shock to hear Calley’s attempted defence that he was following orders, even if it was the only one I guess open to him, seemingly oblivious to the terrible historical resonance of those words.