The first person in the Bible to take a life, Cain, was cursed by the Lord. Was he turned into a pillar of salt, like Lot's wife, or sent plagues like the Pharaoh? No. "You will be a restless wanderer on the earth," God decreed.

Contemporary fighters are often similarly cursed with a restlessness of body, mind, soul and spirit. Today we call it post-traumatic stress disorder, or PTSD, but as far back as 490 BC, the Greek historian Herodotus was marveling at an Athenian warrior who watched the soldier next to him get killed "when suddenly he was stricken with blindness, without blow of sword or dart; and this blindness continued thenceforth during the whole of his afterlife."

About 2.5 million Americans have served (or are serving) in the wars in Iraq and Afghanistan, wars that were approved by our elected representatives in Congress and that we, in the media, stopped covering as often and as comprehensively once it became clear that the mass public no longer particularly cared to read or hear about them.

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A 2008 Rand Corp. study concluded that 20% of military service members who served in Iraq and Afghanistan report symptoms of PTSD or major depression — a conservative estimate, many soldiers I know would argue.

Even so, that's a minimum of half a million Americans walking around with mental and emotional wounds. "I have seen boys like these, younger than these, their arms torn out, their legs ripped off. But there is nothing like the sight of an amputated spirit," says the fictional wounded veteran Lt. Col. Frank Slade in the film "Scent of a Woman." "There is no prosthetic for that." As the wars wind down and policymakers grapple with what is nothing less than a mental health crisis from coast to coast, there are more men and women fighting these tiny wars inside their heads than the more than 60,000 U.S. troops still in Afghanistan.

For "The Good Soldiers," published in 2009, Washington Post reporter David Finkel embedded for eight months with soldiers from the 2-16 — the Second Battalion, 16th Infantry Regiment — in Rustamiya, Iraq, as the "surge" began. For his newest book, "Thank You For Your Service," Finkel embedded with many of the same 2-16 soldiers in Kansas and California as they struggle with their restless wandering, their blindness without blow of sword or dart, their amputated souls.

Sgt. Adam Schumann burst heroically into a battle scene in Finkel's first book. Described as having been "regarded as one of the best soldiers in the battalion," Schumann drapes a gravely wounded sergeant over his back in a fireman's carry. The wounded sergeant's blood spills into Schumann's mouth, a ferric taste the brave soldier can't escape no matter how much Kool-Aid he drinks.

Months later, Schumann, who was on his third deployment to Iraq, leaves on a helicopter designated for the wounded and the dead. "There's not a physical scar," the battalion physician assistant tells Finkel, "but look at the man's heart, and his head, and there are scars galore."

Schumann's battles within his own brain are chronicled throughout "Thank You For Your Service" as well as the intimate struggles with his wife, Saskia, torn between wanting her husband to heal and being frustrated by his absence as he attempts to do so. Finkel is seemingly present for it all, not judging, not excusing, just recording, and thus allowing you to become part of what PTSD is:

"Adam is in the middle of the room, seated on a folding chair. He is faced away from her and holding the shotgun against the underside of his chin. His thumb is on the trigger. The safety is off. To his right is the furnace. To his left are shelves filled with old appliances and the letters he and Saskia wrote to each other when he was in Iraq. In front of him is a taxidermy stand with a faded fish skin on it, onto which he recently had glued a realistic-looking rubber eye.

"So this is where he will die, then."

The book treads beyond one soldier's story; another from Schumann's unit, 26-year-old Tausolo Aieti, attempts to assuage his mental wounds while negotiating a maze of complicated bureaucracy and trying to stay out of prison for domestic violence. Nic DeNinno's anti-nightmare meds are failing as he tries to explain to his wife why his nighttime thoughts about killing prove that he is, or isn't, a monster.

Finkel sketches a panoramic view of postwar life, which includes not just soldiers. James Doster was killed in Iraq; his widow, Amanda, is trying to understand what she's supposed to do now. After a day devoted to helping 49 soldiers like Schumann, Patti Walker, a soldier family advocate, goes home to her wounded-in-action husband, whose facial scars are such that their daughter announced she wanted to dye her hair blue so their fellow customers at Walmart would stare at her instead.

The ones who do not make it, those who take their own lives — and suicides among active-duty military personnel last year outpaced troops killed by the enemy — are discussed in the Gardner Room in the Pentagon, where Army vice chief of staff Peter Chiarelli holds monthly meetings to review the particulars of the previous weeks' suicides. It's Sisyphean: The conversations are depressingly efficient and the potential solutions the opposite.

Finkel's ability to embed in these trenches, recording remarkably intimate moments between husband and wife, social worker and patient, is no less valuable than when he did so near explosions less metaphorical.

He bears witness, seemingly never sugarcoating or judging either the horrors these soldiers are subjected to by ghosts and guilt, or the ones they themselves inflict upon their loved ones. It is a book that every American should read to understand why our easily offered expressions of gratitude — as suggested by the book's title — are insufficient. Whatever one thinks about the wars in Iraq and Afghanistan, we as a society in no small way caused this pain and inflicted these scars. Trying to understand is the very least we can do.

Tapper is anchor of CNN's "The Lead With Jake Tapper" and the network's chief Washington correspondent. His book "The Outpost: An Untold Story of American Valor" was a finalist for a Los Angeles Times book prize; the paperback is released this month.

calendar@latimes.com


Thank You For Your Service

David Finkel
Sarah Crichton/Farra, Straus & Giroux: 272 pp., $26