With an authoritative thrust, Lance Cpl. Jeffrey Rosenthal planted his knee into the back of a fellow Marine from Charlie Company who was lying face down and spread-eagle on a warm patch of desert.

With his thumb and forefinger, Rosenthal, 21, found pressure points at the base of his captive's nose and behind his ear and twisted his head to face the pounding midday sun. Calmly, Rosenthal wrenched the Marine's right arm behind his back and dragged him to his feet. "Get up! Get up, now!" Rosenthal, of Bakersfield, Calif., shouted.

Then he barked a command in Arabic and led his prisoner away to a separate holding area to be interrogated by linguists who spoke Arabic and Farsi.

After months of preparing to fight the Iraqi army, Marines from the 1st Battalion, 7th Marine Regiment have been learning how to deal with soldiers who don't fight back.

In the 1991 Persian Gulf War, approximately 65,000 Iraqis surrendered in the field. This time around, U.S. troops pushing all the way to Baghdad could encounter even greater numbers. Many experts are predicting high desertion rates among Iraqi army regulars, many of whom are young conscripts.

Specially trained civil affairs personnel waiting miles behind the front lines will be responsible for the long-term care of the Iraqi captives, but it will fall to people like Rosenthal to make first contact and secure the prisoners' transfer to the rear.

"If we hit them hard enough, hopefully they will see the light and give up," said Lt. Col. Christopher Conlin, who commands the battalion and was observing the training Saturday morning. The exercises, he said, are designed to make young and relatively low-ranking Marines into what he called "strategic corporals," well aware that their actions toward prisoners "could affect much larger operations."

Taking prisoners is most difficult when the advancing troops are outnumbered by their captives, Conlin said. In one incident during the 1991 war, a platoon of Iraqi armored vehicles surrendered to a four-man Marine sniper team.

Charlie Company practiced scenarios in which several dozen Marines playing the role of Iraqi soldiers surrendered to a squad of just 13 Marines.

Instructors demonstrated the proper technique for a "hasty search," turning up knives, identification documents and other important items stashed in the prisoners' clothing.

The Marines separated officers from enlisted personnel to make the prisoners feel alone and, they hoped, cooperative. Those who had been processed were lined up side by side, with their heads pointing in alternating directions so it would be harder to communicate. Later, the instructors said, a more extensive search would be conducted.

"The job is a lot easier if we shock them right at the beginning. They are supposed to understand that it isn't going to be a cakewalk. It's all about establishing control," said Sgt. Justin Campbell, 23, of Columbus, Ohio, who ran the exercise, barking out instructions and teaching by example.

In Arabic, Campbell ordered a young corporal playing a prisoner to lie down. The man refused. So Campbell took hold of him and swung him around like a rag doll. "You see, he's in a little pain right now," Campbell said.

Campbell jerked the corporal's head straight back so his eyes faced the sky. "This way they can't get a lot of pressure if they want to bite you," he said. "Of course, you only need to do this if they're being insubordinate."

Insubordinate the mock prisoners certainly were. One group started a brawl with their captors that by the instructor's reckoning would have resulted in the deaths of about half of the prisoners and all of the Marines guarding them.

One prisoner jumped to his feet yelling "Allah Akbar!" ("God is great") and was summarily slammed on his back by a Marine standing just a few feet away. Another bolted from his prone position with an ear-to-ear grin and led two rifle-toting guards on a wild goose chase around the large white tents that fill this desert camp. He returned with his smile intact and his face coated in sand from the guards' revenge.

"The initial search is the most dangerous part; after that we feel more at ease," said Gunnery Sgt. Ruy Pena, 37, a reservist from Los Angeles. In recent weeks, he has gone from platoon to platoon, teaching Marines to "search, silence and segregate the prisoners, speedily and most importantly safely."

Once the prisoners are corralled and subdued, the interpreters and interrogators take over, singling out prisoners they feel could provide useful information. "We're an extra set of eyes and ears," said one of the specialists, who asked not to be named.

Cpl. Dale Whitehead, 26, an Arabic speaker from Morristown, N.J., who would work as an interpreter for people interrogating Iraqi prisoners, said the hardest part of his job would be to quickly and accurately relay not just what prisoners say, but what they mean.

Part of the U.S. strategy in this conflict, war planners have said, will be to convince Iraqi soldiers that they will benefit from surrendering. But many Marines said one of their biggest challenges will be distinguishing between those soldiers still fighting and those trying to give up. They could end up shooting a fighting soldier and capturing the one next to him, if he chose to surrender, instructors said.

Those leading the training stressed repeatedly that prisoners must be treated as humanely as possible. "The military is not just about sticking someone in the eye with a bayonet," said Lt. Adam Macaluso of Charlie Company, who was overseeing one of the exercises. The Marines have been instructed to provide captives with food and water rations stored in each combat vehicle. Prisoners are to be permitted to pray five times per day, and, to prevent misunderstandings that could lead to unnecessary violence, each Marine has been taught a few key Arabic phrases. The Marines have also been told never to make a prisoner kneel in front of them, because that posture conjures images of an execution.

U.S. forces must be prepared to fight a "three-block war," said Conlin, the battalion commander: simultaneous humanitarian, peacekeeping and combat missions. Just a few hundred yards from where the prisoner of war training was taking place, another platoon from Charlie Company was running through an urban warfare exercise.

A Marine playing an Iraqi captive is held down as members of his company practice what to do when the enemy surrenders.