Amanda Erickson is an assistant editor of Outlook.

Capt. Josh Mantz has a lot to be grateful for. In 2007, he was patrolling Sadr City in Iraq when sniper fire severed his aorta. He was on the brink of death; his medical team worried that he’d never wake up. Miraculously, he made a full recovery. He even went back to finish his tour. When Mantz finally returned home, people told him he should feel lucky, blessed even. Instead, he felt emotionally tattered and numb. Why, he wondered, had he survived while his staff sergeant died? Could he have saved him?

In her new book, “Afterwar,” Georgetown philosophy professor Nancy Sherman identifies this psychic struggle as “moral injury.” The affliction, she writes, plagues many of the 2.6 million Americans who served in Iraq and Afghanistan. But although we’ve gotten good at treating the physical effects of war, we don’t know how to help returning troops cope with their guilt and remorse. How can we help answer the questions that keep them up at night: Could we have done better, saved more lives, protected the innocent?

Moral injury is difficult to understand, much less treat, because it comes not from what troops have seen, but rather from what they think they could or should have done better. Many vets feel responsible for the death and suffering of their friends, no matter how little control they really had. (Although there is overlap between moral injury and post-traumatic stress disorder, Sherman considers them somewhat distinct.)

Take Marine Eduardo “Lalo” Panyagua. Years later, he still mourns the loss of Corp. Justin Wilson, a teammate (Panyagua calls him his “baby bird”) killed by a roadside bomb when he stepped out of a tank to relieve himself. Panyagua was in a different transport vehicle but still thinks he should have saved Wilson: “I could have said through the radio, ‘Don’t forget to reinforce the area.’ ” As Sherman comments, “In his mind luck — at least this manifestation of bad luck — doesn’t mitigate the obligations of command responsibility.”

Afterwar: Healing the Moral Wounds of Our Soldiers by Nancy Sherman (Oxford University Press)

Another soldier, Tom Fiebrandt, was on mandatory leave from Iraq when he found out that three soldiers in his unit had been killed by an improvised explosive device. Fiebrandt was responsible for mapping out likely IED locations; he thought he should not have left. “Had [he] been there,” Sherman writes, “he is sure he would have recommended against taking that road.”

Fiebrandt was expecting no less of himself than quasi-omniscience. As he eventually realized by puzzling through his guilt, this is an impossible burden.

Self-empathy, Sherman writes, is the way forward for others. And it’s something we need to help our vets achieve. After all, “we have a sacred moral obligation to those who serve.”

Healing the Moral Wounds of Our Soldiers

By Nancy Sherman

Oxford Univ.
226 pp. $24.95