Sebastian Junger says Tribe is his last book about war. As last words go, it’s a good way to end, as this particular monograph may end up shaping—and changing—how the current generation of troops feels about combat and coming home.

“Why is it that you go through this terrible experience of war where you witness death and destruction, and you come home and there’s part of you that misses it?” wondered former-Marine-turned-Congressman Seth Moulton.

“All of the sudden, it all makes sense now,” he said of how the book of helped him understand why he missed his own four bloody tours in Iraq.

Moulton and his brethren came home to a fractured society where almost no one knows their neighbor, and chats by text or Facebook have replaced face-to-face interaction, the antithesis of the cheek-by-jowl closeness of troops in combat. Author Junger, 54, argues convincingly that Americans need to recapture the best part of their tribal beginnings, when small bands of people depended on each other for survival and so developed deep social ties that protect, bind and even heal, as an antidote to the chronic self-centeredness and loneliness that plague modern living.

The slim volume, Tribe: On Homecoming and Belonging, is part anthropology dissertation and part Malcolm Gladwell-style musings on American society, with a dash of how the military experiences war and homecoming. Published in May by Grand Central Publishing imprint Twelve Books, it’s listed as a best-seller by both Amazon and The New York Times.

Anecdotal evidence indicates many of those buyers are in the military. Its ranks are full of fans of Junger’s previous book War, and the Oscar-nominated companion documentary, Restrepo, about a militant-besieged U.S. outpost in Afghanistan. An award-winning journalist and contributing editor to Vanity Fair, Junger spent much of his time in war zones after the attacks of 9/11, ultimately leading to writing Tribe.

“It’s really making the rounds in military circles,” Moulton said of the book, in a telephone interview from his district. “I can’t believe how many people I mention it to and they’ve read it or have it in their bag with them.”

Yet only a small part of the book actually mentions the military.

“The book is miscast as about war,” Junger said in an interview at The Half King, a New York city bar he co-owns. “It’s about modern society and how we’re all affected by the catastrophic loss of communal relations.”

It’s only halfway through the book that he gets around to explaining how that loss is why troops—even those who never actually saw combat—feel bereft when they come home from war zones, missing the brotherhood, the sense of sacrifice and the mission that comes with war.

“You’ve got veterans coming back to a society that not only does it not have that very close human cohesion of your group of people around you, but also seems to be losing its cohesion at the macro level of 320 million people,” Junger said at a book event in Washington, D.C., sponsored by veterans group The Mission Continues.

“Spiritually, this country is bleeding right now,” he added, to nods in the crowd of veterans. “It’s fractured economically, politically, socially,” whether you’re left or right, spiritual or agnostic, he added.

In short, the American community lacks the social skills to connect with each other, much less welcome veterans home. So returning troops don’t miss the blood and guts and mayhem as much as they miss their tribe, or any tribe.

Current and former members of the military stood up and offered their own impressions, at the Mission Continues event at Junger’s invitation, after listening to him give a shortened version of his Ted talk on Tribe.

“After this last tour, I knew that coming home was going to be the hardest thing I had ever done in my entire life,” said Pentagon civilian Dane Bowker of his last combat tour in southern Afghanistan. “There were guys that I absolutely hated in my team, and I would die for them, and I know they would do the same thing for me.”

“I get back home and....I get stuck in a cubicle,” he said. “I make a living, which is great…but that sense of purpose is gone.”

U.S. Army Major Dana Savage spoke of finding the love of her life in war zones, followed by divorce, and feeling disconnected from fellow Americans when she returned home, and now her excitement at returning to an overseas mission.

“To be able to contribute is something that keeps me going,” she said. “You stay physically fit because somebody depends on you. You stay hard to kill.”

“I think as a society, we’ve forgotten how to do that, and we need to go back and teach people what it is to live in this communal tribe and rely on each other,” she added.

Those responses are typical of what Junger has heard on his book tour and through social media.

“What I keep getting is ‘Oh, my god, this is it, this is the thing we’ve all been feeling but didn’t know how to say it,’” he said. “Soldiers, heartbroken ex-wives of combat veterans. It’s endless. The level of resonance that this message had, I wasn’t even prepared for.”

The book helped explain a jarring homecoming many troops experience to former Marine Corps-turned-CIA-paramilitary officer Ian Allen.

“Even with guys who don’t really like you, you assume they will lay their life down for you, and then you come home and it’s this angry nation assuming the worst intent of everyone else,” he said.

Allen dealt with his sense of isolation by returning to serve his previous tribe, helping run nonprofit Third Option Foundation to take care of CIA paramilitary forces and their families.

Allen’s wife took comfort in Junger’s description of his own hypervigilance when he returned from reporting on war in Afghanistan, a state of anxiety where the body is constantly looking for threats, culminating for Junger in panic attacks when he found himself in large crowds. Allen said his wife experienced similar anxiety after her return from two years as a Peace Corps volunteer in a dangerous part of Africa, where she was under constant threat of violence.

“He said something new, and truthful, which is a hard thing to do,” Allen said.

Former Air Force psychologist and Iraq veteran Craig J. Bryan said the book is helping the veterans he counsels to understand why they feel disconnected when they come home.

“The U.S is increasingly becoming a society of individuals where the value system is ‘I want what I want,’” said Bryan, who is executive director of the University of Utah’s National Center for Veterans Studies.

“We have this collectivism in the military,” he said in an interview. “It’s a different value system than when you return home. So you feel like you are pushed outside and separate from the community.”

He said reading the book helps many of the veterans understand it’s not them, it’s all of us. They’re just as disassociated as every other American.

Junger is not without his detractors, nor the book without its flaws, including an apparent error in one of most-quoted phrases in the book—that “roughly half of Iraq and Afghan veterans have applied for PTSD disability,” though only 10 percent of troops are exposed to combat. It was that contrast that led Junger to first question what else troops were missing when they came home, if it wasn’t combat.

In questioning for this story, Junger and his researcher Rachael Hip-Flores tried to find the original source of that statement and determined they’d likely conflated two lines from a single 2012 study, which noted that “45% of veterans of the wars in Afghanistan and Iraq have applied for service-connected disability compensation for psychiatric and nonpsychiatric medical problems,” and noting further that PTSD is the third-most prevalent reason of service-connected disability granted in 2012, after tinnitus and hearing loss.

Junger says future editions of the book will clarify that, and he's also trying to get a more updated figure from the VA, which had still not produced one when this article went to print.

The book’s line stating that 45% of troops had sought PTSD disability was challenged in a Wall Street Journal book review by former Marine David J. Morris. An author and sufferer of PTSD himself, Morris also accuses Junger of claiming PTSD rates are higher than in previous wars, whereas Junger said he was trying to determine if PTSD disability claims had risen.

Dr. Brian Marx, at the VA’s National Center for PTSD, says reported rates of PTSD from Vietnam to current conflicts are actually about the same.

“Rigorous studies of current PTSD rates among veterans suggest that it occurs in 15-20% of both Vietnam veterans and Iraq and Afghan veterans,” he said in a telephone interview. He based that conclusion primarily on a re-analysis of one of the first-ever “population representative” PTSD studies of Vietnam veterans, and a Rand Study of current veterans.

“And the number of veterans who are receiving PTSD compensation is increasing over time,” as is the number of veterans reporting experiencing PTSD, he added, which supports Junger’s assertion that rates of application for PTSD are rising.

Morris also takes issue with Junger’s use of Air Force studies about PTSD in drone pilots, claiming that the Air Force has a vested interest in trying to “humanize the air crews,” which have been criticized for turning war into a video game. Morris, reached by telephone Saturday evening, said he “was not convinced” by the study because non-Air Force researchers had not replicated the study.

VA PTSD specialist Marx counters that it’s not surprising that pilots would develop anxiety disorders like PTSD, especially over the accidental killing of innocents, adding that he considered the Air Force’s testing scientifically rigorous.

As for Morris’s critique of Junger’s observation that PTSD is reported more often by U.S. veterans than by allies like the U.K., Marx pointed out that British veterans report a higher incidence of alcohol abuse than Americans, showing that they may be experiencing the same rates of PTSD, but using different coping mechanisms.

More hurtful for Junger have been the personal attacks in social media echoed in the Wall Street Journal review. Morris quotes an unnamed soldier who calls Junger a “war tourist,” and questions why a civilian who “has never had to dig a fighting hole, fill sandbags or take orders from an idiot who just happened to outrank him,” should be speaking for soldiers.

“He’s basically accusing me of creating a problem where there isn’t one so I’d have something to write about,” Junger said. “I don’t even know where to begin with that one.”

Junger’s defenders have plenty to say, including the army officer who hosted Junger and co-filmmaker Tim Hetherington in the dangerous Korengal Valley, to film Restrepo, which Hetherington wrote about in The Daily Beast. Hetherington was later killed in Libya in 2011.

“Sebastian is one of us,” wrote Lt. Col. Daniel Kearney in an email from Fort Bragg, N.C.

“He filled sandbags with my paratroopers, was shot at with my paratroopers, and he and Tim observed our paratroopers give the ultimate sacrifice. They shared in the blood, sweat and tears with my paratroopers,” he wrote to The Daily Beast.

“His ability to speak on the American Soldier is because he has deployed with him, cried with him, and sacrificed with him,” Kearney added. “Tim’s sacrifice is an example of the position Sebastian speaks from when he writes about our Soldiers and their lives during and after war.”

Junger’s prescription for the rest of us, to emulate the tribe he lived with in the Korengal? Get closer.

“Sometimes people say to me ‘Well, what can we do about this?’ and I say jokingly, well, ban the car. You ban the car, then you’re spending your life within walking distance of your home, and you’re getting to know the people who live near you…because suddenly you’re depending on them, and vice versa.”

More seriously, he called for mandatory national service for American youth, to make them feel like they are serving the nation—and becoming part of a tribe—without having to join the military and go to war.

“National service would allow every young person to experience that,” he said.

As for helping connect veterans with their communities, Junger and Congressman Moulton hope to launch similar events at town halls across America annually each Veterans Day, where veterans can come and speak as they did at the Mission Continues event. The first one was held this past fall in Marblehead, Mass., in Moulton’s district.

“Several hundred showed up,” troops and townsfolk, to hear military stories, Moulton said. “It's the single most rewarding thing I have done since joining Congress,” he added.

Junger himself is trying to take his own advice, creating a tribe where he now lives on the Lower East Side of New York, in an economically mixed neighborhood where safety is sometimes an issue and neighbors pay attention to each other as a matter of courtesy and survival.

“We do look out for each other, in really lovely ways.”

As for his next project, he has no idea.

“I emptied out the refrigerator into my book—everything I’ve been thinking about for the last 30 years about tribal societies and about war,” Junger said. “It's a wonderful feeling. I have absolutely no idea what I’m going to next.”