BAGHDAD » Staff Sgt. Lucas C. Trammell, a tank gunner with the 3rd Infantry Division, fought his way into Baghdad in 2003. He was back in 2005, abandoning the tank for foot patrols in a very unsafe Ramadi, and again in 2007 as bodyguard for a battalion commander in Baghdad.

He has killed the enemy and lost friends. He has sought treatment for post-traumatic stress disorder. ("The Army’s gotten a lot better about letting you put your hand up," he explained.)

He is back in Iraq for a fourth time, part of a force of only 50,000 no longer engaged in combat as of Aug. 31. He is one of thousands of soldiers and officers for whom the legacy of Iraq, like Afghanistan, has been a recalibration of what it means to be an American at war today.

The 3rd Infantry Division has spent more than four years in all in a war that has lasted 7 1/2 years — and may not yet be over. These soldiers, far more than any other Americans, bear the personal and professional burdens of a conflict that has lost what popular support it had at home.

To those fighting it, the war in Iraq is not a glorious cause or, as the old advertisement put it, an adventure. These days it is no longer even a divisive national argument like Vietnam. It is a job.

Even with the formal cessation of combat operations this month, it is a job that remains unfinished — tens of thousands of troops will stay here for at least another year — and one that, like many jobs, inspires great emotion only among those who do it.

"A lot of people at home are tired of this," said Staff Sgt. Trevino D. Lewis, sitting outside a gym at Camp Liberty, the dusty rubble-strewn base near Baghdad’s airport and coming to a point many soldiers made. The people back home can tune out; they cannot.

"The way I look at it, it’s my job," he said, recounting and dismissing the shifting rationales for the war, from the weapons of mass destruction that did not exist to the overthrow of Saddam Hussein to the establishment of democracy in the Arab world. "It’s my career."

The sense of duty among those who serve here, still strong, is nonetheless tempered by the fact that the war is winding down slowly — or, as one officer put it, petering out — with mixed results.

The invasion has left behind a democracy in an autocratic part of the world, but a troubled young one with uncertain control over its security and destiny.

"Do I think the kids running around here have a better future?" Trammell said one evening in Camp Karbala, just outside the holy Shiite city of the same name. "To be honest, I don’t really care. As a nation, was it the right thing to do? In the end of the day, when I look back on it, I haven’t lost a soldier in my squad. That’s what’s important to me."

For the soldiers and officers of the Army’s 3rd Infantry Division, the war in Iraq has become something no one really envisioned when the division crossed the Kuwaiti border on the night of March 19, 2003: a routine.

In Vietnam, draftees served for a year and went home; the professional soldiers of the all-volunteer military fought in Grenada, Panama or the Persian Gulf war with the knowledge they would return quickly, hailed as heroes.

These soldiers in Iraq just kept coming back. They are veterans of not one war but in essence four, each shadowing the shifting arc of Iraq itself: from the "shock and awe" invasion to the bloody sectarian conflict that followed, from President George W. Bush’s "surge" in 2007 to President Barack Obama’s denouement.

Of dozens of soldiers interviewed over the course of their deployments, many said the war was worth the personal sacrifices they made — or the far greater sacrifices of those wounded or killed — but not all did.

For some, the war over time lost the sense of national purpose, or national sacrifice, that might help assuage the hardships of those being asked to fight it.

"I missed the birth of my kid," Sgt. Christopher L. Schirmer said matter-of-factly as he stood guard outside the fortified town hall in Ash Shura, a village in northern Iraq where the embers of insurgency never fully died.

He also said his marriage broke up.

Inside, his company commander drank tea and listened to a local official complain about politics, security, the perfidious media and the need for a bank.

Soldiers like Schirmer are volunteers, banking their tax-free salaries and enjoying the most lucrative benefits any military has ever offered. Most don’t seek sympathy, and they complain no more than anyone would who lived and worked in gravel-strewn camps in dust and searing heat.

Schirmer wears a remembrance of the greater price others have paid: a bracelet engraved with the name of Sgt. First Class Paul R. Smith and the date he died, April 4, 2003, and earned the Medal of Honor. Schirmer was there that day and spoke to him as he died.

"I want a normal life," he said, "enjoy the things Iraq has paid for."

From the intensity of combat during the invasion and the turbulent years that followed, the missions in Iraq today are far more peaceful, reflecting the shift from combat to the advisory role that 50,000 troops will still carry out until the end of 2011.

While soldiers still clear roads of improvised bombs and patrol rural areas in search of insurgents, today’s missions most often involve meetings with local officers or bureaucrats. The military call them KLEs, for "key leader engagements."

"It’s almost not worth the trip," said Staff Sgt. Rodney F. Martin, who is in Schirmer’s squad, then based south of Mosul. "It’s more politics now."

Martin tried to leave the Army after his second tour in Iraq but was forced to stay by the policy known as "stop loss." Third Infantry’s First Brigade was in fact the last unit in the Army to be exempted from the policy, which was rescinded as the personnel pressures on the military eased with the troop drawdown in Iraq, from a high of 170,000.

By the time Martin could leave, though, he had re-enlisted — "The finances weren’t so good," he explained — and now he’s back.

"I think we’ve done all we can do now," he said. "I’m a little burned out."

Some of the younger soldiers complain, too. Roughly half of any of 3rd Infantry’s battalions are new recruits, coming to Iraq for the first time. Some pine for the action of the invasion or the surge or Afghanistan, bored by the relative calm of today’s Iraq.

"I tell them, ‘How we got to this point wasn’t easy,"’ Martin said.

Even as the election gave way to a political stalemate that remains unresolved, the withdrawal proceeded apace.

By summer, Third Infantry’s First Brigade, the U.S. force that seized Saddam Hussein International Airport in early April 2003, began to leave the bases that sprouted around Baghdad afterward and remain to this day.

The latest, in July, was Joint Security Station Mahmudiya, south of Baghdad in an area once known as the Triangle of Death.

Under strict orders, shaped by Congress, they had to inventory everything they took and everything they left behind: tents, generators, air conditioners and even the blast walls.

"Four thousand nine hundred and eighteen," Lt. Jonathan C. Baker said of the concrete barriers. He knew because he had to count them.

Among the things removed was a memorial to those sacrifices, which once stood outside the camp’s operations center, listing dozens of soldiers killed there since 2003.

The company’s orders were explicit: document all the memorials and ship home the ones that could be moved.

One unofficial memorial remained: fading paint on a blast wall commemorating two sergeants and four specialists from Troop E of the 108th Cavalry, part of the Georgia National Guard, who were killed there during the unit’s 2005-2006 deployment.

Time and the elements had worn the names all but illegible.

The wall could not be moved, but the orders were to erase any traces of the U.S. military’s presence on what is now an Iraqi base. Two days later a light blue patch covered it.

"From our vantage point, it’s a victory here," Capt. Alex Zerio, a battalion staff officer overseeing the transfer, said, the base nearly deserted. "You can see. We’re out of here."

For all the support of the nation’s leaders and the public for the uniform they wear, if not for the war itself, none of the soldiers who serve in Iraq have returned home to victory parades.

"It’s not going to be like VE Day or VJ Day," Master Sgt. Noel R. Sawyer said as he prepared to go on a patrol west of Mosul earlier this year.

"Rather than being a defining moment, it’s going to peter out," he said of the end of the war. "In a way, it sucks, but it’s a good thing."

As his armored vehicle rumbled out of the main U.S. base in Mosul, Forward Operating Base Marez, a sign at the gate warned: "Complacency Kills. Stay Alert. Stay Alive."

A blue sign on his MRAP, an armored vehicle designed to withstand improvised explosives planted on roadside — a vehicle that didn’t exist when the war began — said, "We’re on the road with the permission of the Iraqi police."

Both signs were indications, symbols, of how much the war has changed, how much it has wound down already.

Iraq remains dangerous, with U.S. soldiers at risk of attack every day, but since the fourth deployments began late last year, the 3rd Infantry has lost only 14 soldiers, mostly to accidents. Overall 44 U.S. troops have died this year in Iraq, a fraction of the 4,415 killed since 2003.

With combat operations already largely over — with the exception of counterinsurgency raids by U.S. and Iraqi special forces — the soldiers of the 3rd Infantry have served largely as trainers and advisors.

"It’s like, are you OK?" Sawyer said, describing the gradual transition of passing authority to Iraq’s beleaguered security forces.

He stepped back, like a father taking his hands off a child’s bicycle, "Are you OK? Are you OK?"

He stepped back again, grinned widely and raised his thumbs.

The irony is that for many soldiers and officers, the end seems like a victory, if a subdued one, measured in the progress that has been made since the worst days of violence.

"We’re not doing this for a victory parade," said Col. Roger Cloutier, commander of the First Brigade, which after the official end of combat will oversee security for much of Baghdad.

Even so, a parade of a sort was on his mind, his own sense of what has been accomplished after the worst bloodshed in 2006 and 2007.

"When I go to downtown Baghdad, and I’m stuck in traffic, and I’m not jumping curbs, and going against traffic, I’m driving in traffic like everyone else — and I’m looking to my left and right, and there’s a guy selling fish," he said at Forward Operating Base Falcon, a base on Baghdad’s outskirts.

"He’s got a fish cart. He’s cooking fish. And there’s a watermelon stand and then there’s an electronic store right next to it, and people are everywhere. And I’m sitting in traffic and I’m going, ‘Man, this is unbelievable.’ That’s a victory parade for me."

He then talked about his children, ages 9, 14 and 16, sounding very much like a father who had spent much of their young lives overseas.

"I want my family to be able to look at me and say, you know what — I’m getting emotional, guys — when America called, we as a family sacrificed," he said.

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