ARMY COMBAT TOURS There are currently 309,670 active-duty enlisted soldiers who have served combat tours. Percentage of deployments: Source: U.S. Army  Enlarge By Jack Gruber, USA TODAY Staff Sgt. Bobby Martin, right, and Spec. Shamont Simpson, second from left, are on their fourth combat tours. Simpson, Martin and Spec. Carter Dillingham, left, are with 3rd Platoon, Comanche Company, 2nd Regiment, 87th Battalion, Third Brigade Combat Team of the Army's 10th Mountain Division.

At age 34 and finishing a fourth combat tour, he has seen five of his men killed since 2003. Four died this year, including two on Martin's birthday in May. Thirty-eight cumulative months in combat have left him with bad knees, aching shins and recurring headaches from a roadside blast, ailments he hides from his soldiers.

Out of earshot of his troops, Martin concedes, "This is a lot of wear and tear."

American soldiers of the 21st century are quietly making history, serving in combat longer than almost any U.S. soldiers in the nation's past, military historians say.

For many, the fighting seems without end, a fatalism increasingly shared by most Americans. A USA TODAY/Gallup Poll conducted late last week found that 67% believe the U.S. will constantly have combat troops fighting somewhere in the world for at least the next 20 years.

President Obama is sending 30,000 more troops here, expanding a war that by the end of 2010 will be the nation's longest.

The cycles of combat have been so long and so frequent that nearly 13,000 soldiers now have spent three to four cumulative years at war in Iraq or Afghanistan, according to Army records. About 500 GIs have spent more than four years in combat, the Army says.

"Undoubtedly this is unprecedented," says Stephen Maxner, a military historian and director of the Vietnam Center and Archive in Lubbock, Texas.

He says small numbers of soldiers volunteered for multiple tours in Vietnam, but the vast majority served single, year-long deployments in that longest of American wars.

"My grandfather's generation is always called the 'greatest generation,' " says Army Capt. Jason Adler, 33, commander of Charlie Company, where Martin is one of his platoon leaders. "I disagree. It's these men here who go to war three or four times and continue to do what's asked of them, when others refuse."

Fewer than two in 10 soldiers on their first or second combat deployment showed signs of mental illness or reported marital problems, according to battlefield research in Afghanistan completed last year. The rate increased to three in 10 soldiers for those on a third or fourth deployment.

Leaders such as Defense Secretary Robert Gates and Gen. George Casey, the Army chief of staff, acknowledge the increasing stress on the military.

Suicides are at record levels. The divorce rate among enlisted soldiers has steadily increased during the war years. Rates of mental health and prescription drug abuse are on the rise.

With a growing number of injured or wounded soldiers, painkillers are now the most abused drug in the Army. One in four GIs admit to illicitly using narcotic medication during a 12-month period, according to a 2008 Pentagon health survey.

"It speaks pretty well to the fortitude of these folks that they just keep coming back for more," says James Willbanks, director of military history at the U.S. Army Command and General Staff College, Fort Leavenworth, Kan. "But it's difficult to watch, because it's really hard on them, and very, very difficult on the families."

Martin finished his fourth combat tour and rejoined his family on Dec. 31. In the years away at war, Martin missed the birth of his son, Bobby Martin III, 3, in 2006, and has been away for two-thirds of the child's life.

Spc. Shamont Simpson, 28, is another soldier in Charlie Company completing a fourth deployment. He has racked up 42 months, rivaling the 45 months it took the United States to fight World War II or the 48 months the Civil War lasted. Simpson says he barely knows his 7-year-old son, Stefon, from a first marriage.

Both soldiers serve with the 3rd Brigade Combat Team of the 10th Mountain Division out of Fort Drum, N.Y. The division's 1st Brigade Combat Team, about 3,500, deploys to Afghanistan this spring with 20 soldiers on a fifth combat tour and five beginning a sixth deployment, says Staff Sgt. John Queen, a brigade spokesman.

"(I'm) just tired," Simpson says. "Physically tired, mentally tired."

The increasing toll

Without a clear indication of when the USA will once again be at peace, Army research shows that the strain on soldiers can otherwise be eased with extended breaks between deployments. The longer soldiers rest, the better they endure.

When time at home stretches to two years, morale increases and cases of mental illness decline, the research shows.

"(But) it's a very tough trade-off to make," says Army Col. Carl Castro, a psychologist, "between fulfilling operational missions and giving soldiers time to recover."

The Army's aim is to allow two years of recovery for every year in combat. Given the current pace of war, however, it will be a "couple of more years" before that goal is met, says Adm. Michael Mullen, chairman of the Joint Chiefs of Staff. For those in the infantry, who do so much of the fighting, a return to combat often comes within a year.

Meanwhile, soldiers must return to war again and again because the size of the nation's all-volunteer force is limited, Army leaders say. In the past, the government could grow the Army quickly through conscription, allowing the burden of war to be shared by more people.

"It's quite unusual, the inequality," says Christopher Hamner, a military historian at George Mason University in Fairfax, Va. "You've got the vast majority of the American military-aged population that is being asked to do virtually nothing in these two conflicts. And then a very small percentage is being asked to shoulder enormous burdens."

This leaves many soldiers suspicious that other GIs are avoiding combat duty.

"I feel some guys are hiding. Some guys don't want to go. And I think that the people around them just take care of them," says Martin, whose first two combat tours in Iraq were with the Marine Corps before he joined the Army. "(For) us on the line, it's hard to get an assignment to get out."

"The big Army," says Simpson, "they got you in a unit that deploys, they'd rather keep you there then bring somebody in who hasn't."

While there is a need to keep combat-experienced troops in the field, Army commanders say no one is allowed to avoid war duty.

"Every day, we are out there working to identify and to move non-deploying soldiers into deploying formations," says Army Col. Jon Finke, director of the office that manages enlisted assignments.

For the past six years, the percentage of soldiers at any given moment who have not gone to war has held steady at about 32% of the Army, says Louis Henkel, deputy director of the management office.

However, Army records show that when the service accounts for soldiers in training, preparing to deploy, serving overseas in places such as South Korea, in poor health or assigned as drill sergeants or recruiters, there are fewer than 15,000 who can be tapped to fill in for the combat veterans.

These are soldiers who work at the Pentagon and elsewhere, and only a few hundred of those are infantry, says Lt. Col. Douglas DeLancey, who supervises infantry assignments. Most are medical, aviation or military intelligence personnel, Army statistics show.

"We absolutely believe the numbers (available to fill in overseas) are small," Finke says.

The result is that many requests for a break from combat, such as those Martin and Simpson made after their third deployments, are turned down.

The Army has asked the RAND Corp., an independent think tank with ties to the military, to study the issue and find better ways to spell weary war veterans, says Joe Dougherty, a RAND spokesman.

Keeping troops focused

Comparing the soldiers experience for long and hard fighting in different wars is "an imperfect calculus," says Don Wright, a historian and research chief at the Army's Combat Studies Institute. Combat in Iraq and Afghanistan is not as consistently intense as other major American wars, historians say.

But the strain of long and repeated exposures to combat is what makes these current wars historically unique, they say.

"What is exceptional ... is the repeated deployments," says Pulitzer Prize-winning Civil War historian James McPherson.

He says the average Civil War tour of duty was about 2½ years, with small numbers serving for the duration.

"These (current deployments in Iraq and Afghanistan) may take a greater physical and psychological toll than a single deployment, even if the latter is longer," McPherson says.

For the young recruits pouring into the Army and shipping off to combat for the first time, however, these veterans guide the way. The young soldiers of Martin's platoon see him as a disciplinarian whose stern voice keeps them centered during an ambush or when a roadside bomb explodes.

"He's going to be calm so you yourself are not going to panic," says Spc. Don Ezra Plemons, the platoon medic.

"He never wavers. He doesn't show that he's hurt. ... He's always a leader," says Staff Sgt. Kenneth Brook, the company medic, who seeks out Martin for counseling when the stress gets hard.

Simpson has a similar reputation. When a renegade Afghan National Army soldier opened fire with an AK-47 on Oct. 2, killing two American GIs and wounding three, Simpson was first on the scene and moved rapidly to staunch the bleeding of a mortally wounded sergeant.

Pfc. James Radovich, 21, was right behind him, marveling at Simpson's composure and focus amid the blood and chaos.

"He was very calm doing what he had to do. ... He had it under control," Radovich says. "Anything he would say, I would do without hesitation."

But families of both men, weary of the long absences, say the Army needs to relax its grip on these men.

"You keep planning for him to come home," says Joyce Sellars, of her son, Shamont, "and he comes home once, and he comes home twice and he comes home the third time. And you wonder, Lord is this (next) time, the time I'm not going to see my child again."

"It's like, when is this going to end?" his wife Faith Martin says.

It may be soon. Martin has finally been promised a training assignment to Fort Shelby in Mississippi and a period away from war.

"We need this time to work on us and our family," says his wife.

Simpson is guardedly optimistic that he, too, will step out the cycle of combat for a while. So far, he says, "I've got pretty good feedback."