In November 2004, a FRONTLINE production team embedded with the soldiers of the 1-8 Cavalry's Dog Company in south Baghdad to document the day-to-day realities of a life-and-death military mission that also includes rebuilding Iraq's infrastructure, promoting its economic development, and building positive relations with its people.

Filming began three days after the Fallujah campaign was launched in November 2004. There was a surge in violence as an insurgent group, thought to have come from Ramadi, launched a series of ambushes and attacks in Dog Company's sector.

The campaign of violence began when two huge car bombs exploded at Christian churches. The unit responded immediately but found both churches sustained heavy damage. As they returned to base, they were ambushed and came under attack from gunfire and rocket-propelled grenades. They fired back, forcing the insurgents to flee, but in the process a civilian was hit by a ricochet and fatally wounded.

The next day, the situation escalated further. A Dog Company patrol was ambushed and in the fighting Spc. Travis Babbitt, a gunner, was hit. Despite being mortally wounded he managed to return fire before collapsing, killing several insurgents and saving the lives of his fellow soldiers in the process.

Back at the base, patrol leader Capt. Jason Whiteley called his men together to break the news.

"Babbitt was a superb soldier, and he was a great friend to all of us, and he died like he should. He went out fighting," said Captain Whiteley. "We all loved him like a brother, and it's going to be very, very difficult for all of us, including me. But what we have to do now is be strong for the guys who are on the team, for each other…. Because later on tonight, tomorrow morning, we're going to be back on the same road, we're going to be going back into another ambush."

The loss hit the unit hard.

"I don't have a wife or kids. I don't have somebody waiting for me back home, so sometimes I wish it was me, and not Babbitt," says Private Josue Reyes, who at age 19 is the youngest member of the unit and was sent to Iraq straight from basic training.

Later the same patrol was ambushed again, this time with an improvised explosive device known as an IED. One soldier was injured in the attack.

The unit learned that Capt. Whiteley had been personally targeted by the insurgents. He briefed his men on the threat.

"The source stated that due to the killing of a local Iraqi, Capt. Whiteley had been blamed for the death. The relatives had sworn revenge against Capt. Whiteley," Whiteley said, before adding, "I think we've been dealing with an elevated threat level even before this little love note … and we're just going to do things normally. There's no need to get excited about it. People are trying to kill you."

Over the following days, another soldier was killed, and several more injured as the unit embarked on a series of running gun battles and was repeatedly ambushed. The base was hit again and again by mortars and rockets.

The unit went on the offensive in an area that had supported many of the attacks against them, killing at least 24 insurgents.

Senior officers put pressure on local power brokers, telling them in no uncertain terms they must stop the attacks -- or face the full might of the U.S. Army. Rebuilding came to a standstill as the military diverted its resources to destroying the enemy.

Then a lucky break: the Iraqi National Guard found a large weapons cache near one of the mosques which had been at the heart of the many ambushes, including the one which claimed the life of Spc. Babbitt.

Violence began to die down, and the unit returned to the challenging task of nation-building in a hostile land.

"It's kind of like your big brother coming into your room and saying you need to clean your room, and you know how to clean your room and you know, you want to do it yourself, you don't want anybody telling you what to do. Kind of think that's one thing," says Private Reyes.

But the soldiers of Dog Company remained committed.

"After the incident with Babbitt, I was asked if I needed a break, if I wanted to come off the team for a while," says Sergeant Gabriel Garcia. "That's not even a question for me. There's no way I'd leave the team. No way."

"You build a bond here, when you go through life-threatening things every day, when you spend all your time with the same group of people; you sleep with them, you eat with them, you clean with them, you cry with them," says Sergeant Shane Carpenter. "I mean, there's a bond between the men and women I work with out here that I've never felt with anyone else in my life."