The dangers of the assault on Fallujah didn't really become clear to me until Thursday afternoon, Nov. 11. The U.S. military (with journalists embedded with India Company of the 3rd Battalion, 5th Marine Regiment) had already been in the city nearly three days.

We'd seen our share of "Shock and Awe" (the air, artillery and tank barrage as the Marines entered Fallujah (search) was nothing short of a modern-day Dante's "Inferno"). We'd gone along and watched as Marines blasted in doors, scaled walls and turned up weapons and weapon-toters — the blood-thirsty terrorists that this mission was all about.

But again, it took until that Thursday for the difficulty of this campaign to sink in. That's when we watched as Lance Cpl. Clayton South was carried out on a stretcher from a house in the northwestern section of the city.

We'd gotten to know the good-looking 28-year-old Indianapolis native over the prior 10 days as we were specifically embedded with his Third Platoon.

FOX viewers might remember South, too. He was the one who, when I asked what he thought the invasion would be like, replied, "It'll be a walk in the park ... just a little more boom-boom."

He was right on the latter part, anyway. He was leading a "fire team" into the second floor of the house when he opened up one door and found himself face to face with a heavy-set, gun-toting insurgent who opened up on him.

Also caught in the hail of bullets: Lance Cpl. Ray Lopez from Odessa, Texas. His injury touched me as well.

It was this 20-year-old with whom I entrusted my life on the first night of the invasion. In order to make our exit from the assault vehicle (search) as seamless as possible, we attached ourselves to a "fire team" within Third Platoon, and it was Lopez whom we hustled behind into a blinding night of explosions, gunfire and confusion.

Others in that platoon were lightly injured in the Thursday incident before the gunman was very definitively gunned down. But there would be one more casualty that day, and that, too, hit home.

It was the commander of the platoon, 2nd Lt. J.P. Blecksmith. The 24-year-old had graduated from Annapolis last year. He was a likeable guy and had asked my opinion, the night before the invasion was launched, about which DVD he should watch.

The last time I saw Blecksmith he was standing outside the house where the firefight had taken place — where all his young men were a bit scattered and disheveled by the bloodshed and fighting they had just been through.

One of the older officers took Blecksmith aside and told him, "Get a hold of your men ... and get back into the battle."

He nodded quietly and launched a move back into a row of houses where it was thought other insurgents were hiding out.

A half-hour later, as we were with another unit a block away, we got the news: J.P. had been killed, a sniper's bullet finding its way around the upper front corner of his flak jacket, downing the burly fellow, snuffing out an incredibly promising life.

In fact, India Company (which numbers, without added personnel, just over 150) would see three of their Marines killed in action and another 22 injured, 13 of them seriously. But just about none of them gave up the fight — despite some of the most harrowing conditions you could ever dream of.

Imagine entering a strange city, and going house to house, door to door, and behind any door, a guy with a gun might be lurking to try and blow you away.

Oh, and you're not going in the front entrances of these places. Because of the risk of explosives, these guys did their "house-hunting" climbing walls, jumping roofs, squeezing down alleys.

At the end of the mission, depleted by stress and exhaustion, I asked 20-year-old Chicago native Lance Cpl. David Jelinek how many houses he thought he'd gone into.

"A thousand," he told me, "easily a thousand."

These guys easily aged 10 years in a week. They saw it all. Not just their own being killed, but gunning down others, coming across families huddling in the ruined landscape, hauling in detainees — and tons of weapons and explosives in this one-time terror playground.

"It was bad ... it was really bad," Lance Cpl. David Enright told me. He asked me not to give his age (he's got to keep up appearances with some lady friends back home), but this "twenty-something" came into this assault a battle veteran.

He was in on the invasion last year and spent one harrowing afternoon pinned down in a trench in an open field while Saddam's men fired away. He said this was worse. And you could tell by the grizzled look of Enright's face that he'd take an open field over a dark, narrow, smoky house.

A lot has been made in the last few days about the conduct of the Marines in this battle, following a videotaped shooting by a Marine of an allegedly injured and unarmed Iraqi.

I wasn't there and so can't comment firsthand about that act, but I can tell you what I saw with India Company: A bunch of guys doing a back-breaking, nerve-wracking job, in the best way they knew how, with the best conduct you could expect.

Were the Marines I was with on their best behavior because a FOX camera was along? Maybe. But I'd like to think it had more to do with a dedication to achieve the mission — and a dedication to their fellow Marines.

India Company's assault on Fallujah lasted exactly one week. A few houses away from their most southern limit of operation last Monday (they had pushed down two miles from the northwestern part of the city), they came across the biggest grouping of insurgents they would find in the assault.

The commander of India Company, Capt. Brian Chontosh, told me he thinks some 100 rebels were hiding out in that neighborhood. A nine-hour battle would leave at least 22 insurgents dead, another 10 injured and 33 detained.

There were Marine casualties, too, including Cpl. Shane Kielion. He was a real nice kid, always polite and helpful to the FOX team. As a radio operator for the company's officers, he was always in the thick of battle.

On that day, Nov. 15, he was standing on a roof when an insurgent fusillade hit him in the head. I learned later he died from the wounds. I also learned that the 23-year-old had a wife who gave birth to their child on the same day that Kielion died.

India Company is not leaving Fallujah any time soon. Their orders are to stay in the city and see to it that the civilians come back safely and the city gets rebuilt and up on its feet — without the insurgents keeping them under their boots.

It's not going to be an easy job. Most Marines I talked to said it could be rougher than the invasion.

I can only figure, though, that these guys will work a little harder on that future mission because of their colleagues who have fallen fighting the mission just wrapped up.

Greg Palkot currently serves as a London-based senior foreign affairs correspondent for Fox News Channel (FNC). He joined the network in 1998 as a correspondent. Follow him on Twitter@GregPalkot.