“The moral basis of the war doesn’t seem to interest soldiers much, and its long-term success or failure has a relevance of almost zero. Soldiers worry about those things about as much as farmhands worry about the global economy, which is to say, they recognize stupidity when it’s right in front of them but they generally leave the big picture to others.”

The book War isn’t about the politics of the Afghan conflict; it’s about the American soldiers deep in enemy territory and how they think and feel about battle. What concerns them is staying alive, protecting their fellow soldiers, and giving hell to the enemy; they can’t afford the luxury of opinions about world events or the wisdom of their unit’s involvement in a controversial war.

“Wars are fought on physical terrain—deserts, mountains, etc.—as well as on what they call ‘human terrain.’ Human terrain is essentially the social aspect of war, in all its messy and contradictory forms. The ability to navigate human terrain gives you better intelligence, better bomb-targeting data, and access to what is essentially a public relations campaign for the allegiance of the populace.”

Soldiers on both sides in Afghanistan must win the hearts and minds of local populations. A victory over a piece of territory may cause so much trouble for civilians that the larger battle is lost. If the fighting causes problems for a village or injures or kills some who live there, residents may overlook the new construction, water lines, and other benefits provided by the outsiders and rise against them.

“I once asked O’Byrne to describe himself as he was then. ‘Numb,’ he said. ‘Wasn’t scared, wasn’t happy, just fucking numb. Kept to myself, did what I had to do. It was a very weird, detached feeling those first few months.’ ‘You weren’t scared of dying?’ ‘No, I was too numb. I never let my brain go there. There were these boundaries in my brain, and I just never let myself go to that spot.’”

O’Byrne’s platoon is in the center of the worst fighting in Afghanistan. With daily firefights, troops dying, and blistering heat, the stress level is overwhelming; the men do what they can to stay alive and sane. It takes time for the platoon to coalesce fully, coordinate, and begin to fight efficiently; until then, tension and uncertainty have the upper hand.