On this memorial day we honor America's servicemen and women. And tonight you're about to meet soldiers who formed a brotherhood so strong while serving in Afghanistan they found nothing could replace... See More
On this memorial day we honor America's servicemen and women. And tonight you're about to meet soldiers who formed a brotherhood so strong while serving in Afghanistan they found nothing could replace it. A new documentary takes us inside the brutal and harrowing battles they fought so far from home. And while the fighting was tough enough, in some ways they say coming back was even tougher. Here's ABC's Brian Ross. Reporter: What happened in this ruggedly beautiful faraway country became known as the other war. Even though more than 2,300 Americans have so far died in Afghanistan, in fighting as fierce and as difficult as anything ever seen by the U.S. Military. Did you see him? No, I don't see him. Yeah, it's frightening. I think if anybody told you they weren't scared they were kind of You. You're scared. You know that fear is there but you just put it away. Reporter: Most of the fighting and dying in Afghanistan happened in remote places that few Americans ever heard much about. Down low. You're doing good. Reporter: Like the area around the U.S. Outpost called Restrepo, a six-mile-long korengal valley, near the border with Pakistan. Some 42 Americans were killed in the korengal valley. And for those who served here with them, today is very special. I think memorial day's a very powerful day for them. This is the day where they really think about, like my god, that guy died at 22. What a sacrifice. It's a very solemn time for them. Reporter: Over the course of more than a year journalist Sebastian junger along with photographer Tim hetherrington were embedded. They produced award-winning reports that aired on ABC news and a feature-length documentary called "Restrepo" that was nominated for an academy award. And now with American forces being drawn down in Afghanistan junger has a follow-up film called "Korengal" that provides a rare and surprising insight into why some American soldiers may actually wish they had never left Restrepo. It's a giant machine gun. What's not to like about a giant machine gun? Soldiers miss war. What is it they're missing? I really wanted to make a film that got into the soldiers' minds and helped them and the country obviously understand what that experience is like. Is there anything about this you're going to miss? Shooting people. It's always fun shooting. Is there anything you miss about Restrepo? The6a I think a lot of us kind of miss that adrenaline. Americans have a kind of war fatigue. But not these soldiers. It was the most intense thing they've probably ever done. And you know, of course they don't miss getting shot at and they don't miss having to shoot at people. But what they do miss is that brotherhood of combat. It's not replaceable back home. And I think that's the sort of secret to understanding why soldiers can miss something that's as terrible as war is. There's nothing else like it. We're getting engaged again. Reporter: At times-w scenes set to a pounding rock beat, it seems not unlike a violent video game come to life. Whoo, hoo! Fire! Combat's a lot of things. And among other things, it's intoxicating and very high adrenaline. And those guys were jacked out of their minds in that firefight. By the same token, there's other moments in the film and in real life where you're in this sort of like, you know, moral freefall into this sort of darkness, like what are we doing? We're killing people, we're dying. Whoo! For a while there I started -- I started thinking that god hates me. And like I said, I'm not religious or anything, but I felt there was this hate for me because I did sin, you know, I sinned. And although I would have done it the same way, everything the same exact way, I still would feel this way. You know, I still -- that's the terrible thing with war. Any honest film about war captures those two truths. It's very, very -- combat's very exciting. And it's profoundly disturbing. That comment, you did what you had to do, just drives me insane. Because is that what god's going to say? You did what I had to do. Good job. Punch you on the shoulder and say welcome to heaven? You know. I don't think so. Reporter: The mission of American soldiers in Afghanistan over the last 13 years was to go after the Taliban and Al Qaeda, considered vital to national security. For these soldiers that meant leaving the protection of their hilltop base and heading down to the villages below to win over the hearts and minds of the villagers. When we left the wire, most of the guys were scared, and what was going through their mind was hopefully I don't get to die today. You know, hopefully I live to see another day. They're going to talk to you guys -- Reporter: But junger's film reveals the seeming futility of the mission and the contempt in which each side regarded the other. We come in, they're going to take what they can get from us, and then as soon as the Taliban comes in they're going to give them what they want, but they're a little more scared of those guys than us. So I think they played both sides and they'll be fine to your face but in the end they're just kind of in the middle trying to survive. You know, this whole going there and act like they're friends thing doesn't work. Hearts and minds is out the window when you see the guy shooting at you and then he puts his wife and kids in front of him knowing full well that we won't shoot back. Women and children up on the roof. Or the guy who shakes our hand, takes the ten bags of rice we give him for his family, the school supplies, and immediately walks through the mountain, shoots an rpg at us, walks back down and smiles at us. His heart. His mind. Reporter: The U.S. Withdrew most of its forces from the korengal valley some four years ago. Junger says in the minds of American commanders the mission at Restrepo served a larger strategic purpose in stabilizing the area and holding the Taliban at bay, even if the soldiers in the korengal valley didn't always see the bigger picture. Once you're out there, you know, your country's an abstraction. Once you're out there, what you're really doing is fighting to survive and help your brothers survive. And that's really it. And I think that's been true for millenia. I think the Greek soldiers at the walls of troy didn't really care about Helen. Right? They were fighting because they were there with their brothers and that's what was happening. And some of the most telling moments in junger's film come in between battles, waiting for the next mission or the next attack. I've been hit! What does courage mean? I would ask them that. Like what does courage mean? What's it mean to be brave? Bravery to me, as an example would be something along the lines of someone who goes out of their way despite the very likely potential of dying and risking his life to, you know, protect another one. We didn't talk about that word very much because we didn't feel what we were doing was bravery. Every single person that got shot over there, they didn't worry about themselves one bit. All they asked about was how are my guys? Sergeant rice when he got hit, he's like where's my team at? Is solo okay? Is Jackson okay? Is vandenberger all right? Sergeant Padilla lost his arm. His arm S missing. He had shrapnel in his face. And he was just asking if everybody was okay. That's bravery. Sergeant first class Cortez, unwavering courage, aggressiveness, and leadership while under fire were decisive to his company defeating an enemy attack. Private first class Cortez's performance reflects great credit upon himself, task force bayonet, combined joint task force 101. How'd that feel? Awesome. Yeah? Felt good? Felt good. You guys looked proud up there. Of course. We accomplished something. We got recognized for this. I'm happy. You didn't start crying or anything. No. I'm not sentimental like that. I don't break down. I'm a soldier. But there were times when they did break down. When the tears flowed. Yeah, they're all trying not to cry. And of course they fail. Yeah. It's very powerful.
This transcript has been automatically generated and may not be 100% accurate.