FORT RILEY -- During the Mexican War, its lieutenants included Robert E. Lee, George McClellan and P.G.T. Beauregard. The unit became known as the "Diehards" after fierce fighting in North Africa during World War II.

History of 1st Engineer Battalion By The Associated Press NAME: 1st Engineer Battalion, 1st Brigade, 1st Infantry Division. POST: Fort Riley, Kan. ORGANIZED: May 15, 1846. CAMPAIGNS: Mexican-American War, Civil War, Spanish-American War, Philippine Insurrection, World War I, World War II, Vietnam, Persian Gulf War, Kosovo, Iraq. CURRENT DEPLOYMENT: Iraq, since September 2003. MOTTO: Always first! Diehard! DISTINGUISHED ALUMNI: Robert E. Lee, George McClellan, P.G.T. Beauregard, Sgt. Major Frederic W. Gerber (Medal of Honor recipient, Civil War), Sgt. Wilber E. Colyer (Medal of Honor recipient, World War I), Diehard Tunnel Rats who cleared the extensive Vietcong tunnel systems. HONORS: Presidential Unit Citations, World Warr II: Gafsa, Tunisia and Normandy; Valorous Unit Citation, Iraq-Kuwait; Meritorious Unit Citation: Vietnam 1966, Vietnam 1966-67, Vietnam 1967-68,Vietnam 1969; French Croix De Guerre, World War I: Lorraine-Picardy, Aisne-Marne and Meuse-Argonne; French Croix De Guerre, World War II: Kasserine and Normandy; Fourragere in colors in French: Medialle Militaire; Belgian Croix De Guerre, World War II: Mons, Eupen-Malmedy; Forurragere in colors in Belgian: Croix De Guerre. Source: http://www.diehardengineer.com/

For the past nine months in Iraq, the unit has been clearing obstacles for the infantry, battling insurgents and seeking out weapons left from ousted dictator Saddam Hussein's reign. Its duties have often put its engineers under fire, and it has seen more deaths in the Iraqi war than any battalion from Fort Riley.

The 1st Engineer Battalion of the 1st Brigade in the 1st Infantry Division, formed in 1846, is the U.S. Army's oldest engineer battalion, and its soldiers have come to expect that they'll end up in a conflict's toughest fighting.

"We prepare the road so the infantry can go in and fight," said Terry Hueser, a retired Army captain who served in the 1st Engineer Battalion in Vietnam. "We basically go in and open the avenues of approach."

Since deploying in September, 10 Diehards have died, including five in March when a bomb exploded beneath their M113 personnel carrier. In all, 37 soldiers from Fort Riley have died in Iraq.

The battalion earned its nickname 62 years ago, during the campaign in North Africa.

"The battalion, fighting as infantry, refused to yield, and a captured German officer remarked that the battalion was hard to kill, it died hard," Lt. Col. Dave Brinkley, the unit's commander, said in an e-mail from Iraq.

Two years later, the Diehards cleared the beaches on Normandy as the 1st Division participated in D-Day operations, earning a Presidential Unit Citation. In 1980, the film "The Big Red One," written and directed by 1st Infantry Division veteran Samuel Fuller, chronicled many of the fights the Diehards encountered.

Hueser, who served in Vietnam during the 1968 Tet Offensive, spent the past year in Iraq recruiting soldiers to serve in the new Iraqi army.

"We were one of their big targets," Hueser said, referring to insurgents who attacked recruiting stations in Baghdad and Mosul -- shortly after Hueser had left each place.

The battalion deployed in September with the rest of the 1st Brigade. Since arriving, soldiers have been conducting weapons sweeps and reconnaissance to ensure traffic routes are clear of mines, obstruction and improvised bombs.

"The battalion is doing well in light of the increased fighting and our unfortunate losses," Brinkley said.

In Iraq, Hueser linked up with Diehards passing through Baghdad and said most were astonished to find "an old guy" was in the country. Then, he told them about his days in Vietnam.

"It holds a special place with all the soldiers," Hueser said of the Vietnam War. "That was the last really long war that we fought."

Hueser said he wanted to visit the battalion, but heavy fighting around Ar Ramadi, where the soldiers are deployed, would not allow it.

While a political debate continues nationally about how much the war in Iraq resembles Vietnam, Hueser said the mood of the current soldiers is better. He said they are facing similar combat techniquest, where enemies blend into a crowd and wait at alleys and checkpoints.

"You're fighting an enemy who you don't know who he is. You don't know where he's going to hit next," Hueser said.

Improvised explosives, such as pipe bombs and modified artillery shells, have replaced the land mines and booby traps of Vietnam, he said, making the job of a combat engineer more valuable -- and dangerous.

Brinkley said the battalion has been too busy to focus on the losses, and its work is paying off. He said the unit's soldiers have reduced insurgents' weapons and ammunition stocks and made their homemade explosives less effective.

Meanwhile, at Fort Riley, Capt. Terrence Alvarez, 30, of Trenton, N.J., and other members of a rear detachment link Diehards with their families and keep them supplied.

A classical literature major from Gettysburg College in Pennsylvania, Alvarez said, "The Army made me an engineer." He has been with the battalion for four years.

"Obviously, the history plays a lot. There's a certain amount of pride in that," Alvarez said.

Capt. Thomas Swint, 29, of Salem, Ore., said the battalion is particularly tight knit, having about half the strength of a traditional infantry unit. The unit often does the difficult.

"Every engineer I run into follows our motto: 'Let us try,"' Swint said. "The engineers die trying."

Hueser said many of the unit's Vietnam veterans are reviving their past through the unit veterans' group, as a means of reflecting on their service to the country.

"You figure it out when you put on the uniform and put on the patch: You realize that you are part of something special that goes back the formation of the armed forces," he said.

Brinkley updates veterans about the Diehards' current mission by posting comments on the unit's Web site.

"I know my service with the 1st Engineers is and most likely will be the highlight of my life, and I will always be a part of the battalion, at least in spirit," Brinkley said.