Then the mood shifts. Something is suddenly understood, it appears on the faces of the doctors. There is a pulse, nothing more. The soldier doesn't react to stimuli, shows no signs of life. There is a question about what to do. But Mitchell must leave, speed dictates, and we fly back to base to wait for the next call.

On the ground we learn the soldier's fate. Doctors discovered a metal fragment embedded deep in his brain. They decided an operation would be futile. The only hospital equipped to do that kind of brain surgery was too far away, in another part of Iraq. They pumped in pain meds, just in case, and waited for his heart to stop. For Mitchell, the flare of triumph dies. He looks at me blankly, then walks away, saying nothing. It doesn't always end like this. But these are the days the crews must get used to, the ones they never forget.

In Iraq, one massive U.S. military machine fights the war. Another cares for those injured in battle. The effort is enormous, unrivaled. Medical procedures and body armor have vastly improved since America's last comparable war, in Vietnam. Yet the techno-sheen given this war by smart bombs, night-vision goggles, and remote-controlled drones is misleading. It is not miracle technology that saves lives on the battlefield in Iraq. The most important tools are tourniquets, the most important methods timeworn.

Trauma care proceeds in stages. It begins on the battlefield, with medics pulling bandages from their backpacks, often under fire. Some wounded are then rushed to small field stations like the one at Al Taqaddum, where Navy surgeons operate on marines fresh from the urban hell of Ramadi.

Others are airlifted directly to larger hospitals such as Ibn Sina, a former Baathist facility, where the wounded arrive around the clock. When they are stable, patients are flown, IVs snaking from their bodies, nurses monitoring their vital signs, to a military hospital in Germany. Then, at last, they return to the United States for final procedures, recovery, family.

All this can happen in as few as 36 hours. The process rivals FedEx in complexity and tempo. Soldiers become warm packages, bundled and gently tended, hurtled across time zones in the bellies of cargo planes. Often they are drugged and remember little of the journey, waking in hospitals in Washington, D.C., or San Antonio, Texas, to find their worlds, their lives, have changed. For soldiers arriving in the "sandbox," as Iraq is often called, knowledge of this global lifeline boosts morale and relieves some of the stress that comes with heading into battle or patrolling roads clotted with bombs.

At Ibn Sina, the largest Army hospital in Iraq, staff boots tell stories of war. In calm hospital wings, boot tops are soft and clean. In the trauma room, they are splotched and matted with blood. The floor is a dump, often slick with red pools, littered with bandage wrappers, scissors, shreds of clothing, charred skin. Boots are necessary. At the nurses' station just inside the hospital entrance, all the boots have been baptized in blood.

It is lunchtime. Young medics and nurses cluster at the large wooden desk laughing and joking. Some wear surgical clamps clipped to their pants, always ready, just in case. Others tuck tape and syringes into their pockets. Nearby, Iraqi janitors swing mops lazily along marble floors that Baath Party elites, including Saddam Hussein and his family, once crossed on their way to receive privileged medical care. There is a faint odor of disinfectant and feces.

The staff at Ibn Sina is part of the Army's 10th Combat Support Hospital, or 10th CSH, pronounced "cash." Many of the war's worst casualties, from wounded coalition and Iraqi personnel to civilians and insurgents, are helped here by some of the best trauma teams in medicine. The hospital treats hundreds of patients each month. It does not mirror the sleek, high-tech civilian institutions in the U.S. or Europe. It is battle-ready and rough, the rooms cluttered with equipment, some of it aging. Occasionally, the electricity fails.

But then, war medicine is not civilian medicine. It's dirtier, faster. The wounds are worse, the patients at greater risk. Here medical teams cut, crack, and inject where their civilian counterparts might pause and worry about lawsuits. Ibn Sina is designed for life-saving procedures, not the long recoveries required by amputees or burn victims. The mission is simple: stabilize patients, ship them on to facilities equipped for longer term care.

"There are no litigious restrictions over here," a lieutenant colonel who is also a doctor tells me. "People play fearlessly, and when they play fearlessly, they make fewer mistakes. It's a dose of reality you'll never forget. The surgeons, nurses -- never in the rest of their lives will they be who they are here."

The 10th arrived here in October 2005 to replace another CSH unit at the conclusion of a year-long tour. Few of the 10th's nurses or medics had ever seen the chaos of big trauma. Many are in their early or mid-20s; some had cared previously for cancer patients or the elderly. Iraq was immediate, terrifying immersion.

Lt. Col. John Groves, 42, head ER nurse, trained in some of America's busiest trauma centers, including Miami and Honolulu. He is a short, friendly man, a career soldier who, if prompted, can talk into the night about past cases and calamities, the mutilations of this war. He is a self-described steel-mill kid from Indiana, and on his desk lie photos of the 20 or so head of cattle he keeps on his new farm in Kansas, where he plans to retire.

Groves is a father figure to his young staff. He watches them carefully, knows their strengths, their weaknesses. He remembers thinking not all of them would last. "So many were timid, they didn't know what to do. It was a hard adjustment, and not everyone is cut out for this kind of medicine." Groves was ready to reassign several nurses to other wards. Lt. Riane Nelson was one of them.

She is 24, a tall round-faced blonde from San Diego with blue-green eyes that shift color depending on the scrubs she wears. From the time she was eight, she wanted to be a nurse. She lived then in Greece, where her parents worked as missionaries. After college, she joined the Army. She didn't have any trauma training before she arrived in Iraq.

Nelson grew up an athlete. She knew what it meant to work hard, play fast. But she struggled with the crushing pace of the trauma room, the weight of decisions made amid blood and fading lives. She forgot things, made mistakes. She began, she says, to crack. Then, slowly, the weeks of panic yielded to smoothness. She remembers when the conversion came.