I can see them now in my mind's eye. Still remember their faces, hear their voices. I probably always will, for war has a way of etching the memories of people, places, smells and sounds on the psyche as few things can.
I think of men such as Private James Little, an American infantryman with the Stryker Brigade who one day, during a search-and-destroy mission in Baghdad's badlands, drew heavily on a Lucky Strike and told me how his buddy had just been blown to pieces by a roadside bomb.
"Motherf***ing thing looks just like some big copper ashtray, but heats up on detonation and goes straight through the armour like a hot knife through butter," he recalled, as we sat huddled behind a wall during a lull in fighting in the Mansour district of the city.
"It blew in, hit Lucas in the side and in his face," he said, before his voice tailed off, as if suddenly seeing Lucas in his own mind's eye.
Just listening to him, you knew that image had already turned to black and white in Private Little's head. It would never leave him.
More recently, just a few weeks ago in fact, I met a 22-year-old British marine called Ryan Gorman in Helmand, Afghanistan. As a sniper with 45 Commando, his mental snapshots were of a different kind.
"Lots of the lads here when they fire back are shooting at shapes and blurs, but I could draw you a picture of the men I see, even the features on their faces."
Being a sniper is not something Gorman likes to talk about when back home in East Kilbride. "Even my closest mates wouldn't understand," he confides.
But then just who, other than soldiers themselves, could ever be expected to understand such experiences? How many of us can honestly relate to what it must be like to watch a close friend die horribly in battle, or carry the psychological weight of having "confirmed kills" attributed to you?
Since that day in September 2001 when the twin towers buckled to the ground in New York, have we ever really paused to consider what impact the prosecution of the "war on terror" has had on a generation of our own young men and women who have served in Iraq and Afghanistan?
To some, of course, soldiers such as Little and Gorman seem at best the naive stooges of political overseers hell-bent on oil-grabbing and the relentless pursuit of our nation's imperial ambitions. At worst, servicemen like them are castigated as a latter-day breed of "babykillers" just like their predecessors in unpopular wars such as Vietnam.
These modern soldiers and marines after all, appear far removed from that "Greatest Generation" who stormed the beaches at Normandy and pushed back fascism. Today's warrior crop, it is often assumed, are not made of the same stuff, having been weaned on video games, the internet and reality TV.
I remember once, just before a dangerous night time "isolation operation" in western Baghdad's Iskan district, seeing American soldiers from Charlie Company 1st Battalion 23rd Infantry watching Sean "P Diddy" Combs on the Conan O'Brien Show at their forward operations base (FOB). One minute they were howling with laughter, the next they were listening to their company commander briefing them on the high chance of contact with the enemy and taking casualties. So much of war is like this, full of morbid interruptions and surreal eccentricity.
Ever since 9/11, the burden of fighting Iraqi insurgents and the Taliban in far-flung places like Fallujah or Helmand has fallen heavily on the shoulders of young soldiers such as these.
In Generation Kill, the new seven-part mini-series set in the Iraq war, the creators have tried to paint a portrait of this new breed of men at war. Based on a true story and told through the eyes of embedded reporter Evan Wright of Rolling Stone magazine, it is an uncompromising, roller-coaster tale of men from First Reconnaissance US Marines, whose job it was to "spearhead the blitzkrieg" on Iraq.
As you would expect from the pairing of David Simon and Ed Burns, who also created the acclaimed Baltimore cop series The Wire, Generation Kill has been made to smack of authenticity. Tim O'Brien, a former infantryman turned writer and one of the best chroniclers of the Vietnam war, once commented that "a true war story is never moral". As O'Brien saw it - and he saw a lot during his time in Vietnam - you can tell a true war story by "its absolute and uncompromising allegiance to obscenity and evil".
Generation Kill certainly has both in abundance, and within the ranks of its character are the stereotypes so many of us assume to be commonplace on the front lines of Iraq and Afghanistan.
"You know what sucks? All those dead people we saw today and I didn't get to shoot one of 'em," complains Lance Corporal Harold "James" Trombley, a teenage "jarhead" and the least experienced marine in Generation Kill.
Trombley's character is typical of what Wright calls "America's first generation of disposable children. Young men from broken homes often raised by absentee, single working parents more acquainted with internet porn than they are with their own parents."
As Trombley quips in true video gamer style, after his unit seizes an Iraqi town, "It was just like Grand Theft Auto."
Over the years I've met many Trombleys in Iraq and Afghanistan. A few of these "Joes" have clearly long given up caring about such things as protocol or basic courtesy regarding the Iraqis they encounter. These men think nothing of dropping cigarette butts or spitting chewing tobacco on the floors of Iraqi family homes during house-to-house searches. Sometimes, they've been known to do much worse things.
For them the "Hajis" have replaced the "Gooks" of the Vietnam era, and are nothing more than a threat to their lives. Politics, the war on terror, making America safe - none of that matters half as much as staying alive and getting home.
Perhaps the badlands of Baghdad have worn them down, burned them out emotionally. Then again, perhaps they were always like that.
If one of the great strengths of Generation Kill is to confirm the true existence of such abhorrent stereotypes, then another is the drama's ability to reveal that not all soldiers are borderline psychotics or racists. It might be difficult for many of us looking on from the safety of home to believe, but some men do love soldiering, revelling in the exotic, high-octane experience of war and the consummate professionalism they are trained to bring to the chaos of the front line.
As a reviewer once wrote about the author of Dispatches, Michael Herr's book about the Vietnam war: "Herr dared to travel to that irrational place and to come back with the worst imaginable news: war thrives because enough men still love it."
In the pages of Dispatches, Herr often referred to his British war photographer friend and colleague, Tim Page, who when once asked if it was possible to take the glamour out of war replied: "Take the glamour out of the war?! I mean, how the bloody hell can you do that? Go and take the glamour out of a Huey, go take the glamour out of a Sheridan Can you take the glamour out of a Cobra or getting stoned on China Beach? Oh war is good for you, you can't take the glamour out of that. It's like trying to take the glamour out of sex, trying to take the glamour out of The Rolling Stones I mean, you know that, it just can't be done."
Some years ago, after the war in Vietnam was long over but the civil war next door in Cambodia still rumbled on, I ran into Tim Page in Saigon, and asked whether he had really meant what he said and stuck by it. "Of course," he confirmed. "You've been there, you know what I mean."
I do know what Page meant, but, unlike him, it was never something I relished. That's something I was sharply reminded of just a few weeks ago, after being caught in a Taliban ambush while on a mission with 45 Commando Royal Marines in Sangin Valley, Helmand.
Though a specifically American take on the lives of their own marines in Iraq, watching Generation Kill is to be reminded of the universality of the front-line soldier's experience. The boredom, the profanity, the high-tech virtually impenetrable language of a close-knit community, and above all the black humour.
I remember sitting aboard a Blackhawk helicopter at Baghdad International Airport (Biap) once, heading for a remote FOB. Next to me, a soldier wearing the shoulder patch of the "Screaming Eagles" 101st Airborne Division grinned and handed me a piece of paper on which there was a caricature of some newly arrived American soldiers at Biap.
Behind them lay an apocalyptic landscape of smoking, bomb-blasted buildings full of dismembered bodies littering the streets. Sticking up from the devastation was a signpost on which was scrawled in blood-red letters the words: "Welcome to Baghdad." All the cartoon soldiers stared at the sign except one, who, from the corner of his mouth, urgently asked his buddy. "If God blessed America, then why the f*** are we here?"
Like the humour, the customs, codes and language of the soldiers existence is unique. A world of FOBs and MREs (Meals Ready to Eat), where to watch the enemy is to have "eyes on", and fight them results in "kinetic" activity. Here, if you are an American marine, your clarion call is "Get some" and if you're British it's "Crack on".
To those of us outside this military fraternity, it's all too easy to see those in uniform simply as heroes or villains. As is so often the case, the truth behind their role, like the motives that took them to war zones in the first place, is often far more complex.
In Afghanistan recently - while living among the men of with 45 Commando on FOB Inkerman, a Vietnam-style firebase frequently the target of Taliban attack - I was constantly amazed by the mental and physical resilience of those who manned this remote and dangerous outpost.
After one fairly "kinetic" afternoon during which we had more "contact" with the Taliban than I had comfortably wanted, the look of professional satisfaction on the faces of the men who had returned from the mission said it all.
"The lads relish it," said Major Richard Parvin, the officer commanding Yankee Company, his grin as big as those on the faces of his men. Not for a second had I any reason to doubt that what he said was true.
Politically, the wars in Iraq and increasingly in Afghanistan remain a hard sell. For that reason too, Generation Kill might prove a tricky proposition when it comes to ratings, but few who have been near a front line would question its claim to authenticity.
An American take it might be, but a universal tale of today's soldiers' life it most certainly is. Whether those who comprise this current generation of warriors will in the years to come be blighted by their experiences in Iraq and Afghanistan, only time will tell. After all, getting into a fight is one thing. Getting out, however, will be like having one of those tattoos so beloved of bootneck marines surgically removed - slow, painful and scarring.