WITH U.S. FORCES, NORTHERN SAUDI ARABIA, FEB. 18 -- One night soon, Marine Lance Cpl. Stephen Mitchell, 20, expects to drive a 26-ton mine-breaching personnel carrier across the Kuwaiti border and into a sandy sea of buried mines.

"I'll be one of the first ones across the line," said the lanky Washington, D.C., native, unconsciously fingering the two metal crosses that hang from a silver chain around his neck -- one sent by his mother, the other by his aunt. "Sometimes I sit and wonder, and try to picture in my mind what it will be like."

All too frequently the picture is horrifying.

"In training, there is always one little thing that will go wrong," he said with a shudder. "It gets you down. Will it happen in combat? It's real hard, real hard."

When the traveling chaplain, or Mitchell's buddies who sleep with him inside the hulking metal vehicle dubbed "The Big Red One," can't console him, Mitchell relieves the pressures on his mind by "going to the paper and pen and writing it down."

Often he mails his deepest thoughts to his girlfriend. He has pasted her picture inside the personnel carrier that will push his team of mine breachers ahead to clear the way for the American tanks and infantry units that will battle Iraqi forces.

For many of the thousands of American troops now moving into their final positions across the northern Saudi Arabian desert, within sight of the nightly allied bombing raids against Iraqi forces, the easiest mental escape from the formidable task that lies before them is simply avoiding the issue.

"Most people don't talk about what happens when we go in," said Navy medical technician Douglas Smith, 35, of Baltimore, a reservist on the crew of a mine-plowing tank who will serve as a medic if his crewmates are injured. "They speculate about when we will go home. They don't talk about that gray area in between."

Instead, they lose themselves in long card games. They gaze across the flat Saudi desert now covered with the green fuzz of sparse winter grass, and fantasize about showers they haven't had for more than a month and hot meals they left behind weeks ago.

They wiggle into sleeping bags on the cramped floors of personnel carriers and in tiny tank turrets, and dream of soft mattresses and wives and girlfriends half a globe away.

But mostly they work, struggling to keep aging equipment operating in the gritty sand of the desert, miles from the nearest stocks of spare parts and supplies.

"We are constantly, constantly repairing the tank," said Sgt. Nelson Carter, 25, a reservist from Knoxville, Tenn., the senior non-commissioned officer for one team of 11 specially designed tanks.

Both the men and the machines of these mine-breaching teams have been patched together from different bases across the United States for a one-time mission: to slice through the minefields that lie between allied troops and the deeply entrenched Iraqi forces across the border.

They have stuffed amphibious personnel carriers designed for beach assaults with the explosives needed to blast mines from the sand, and they have tacked toothy plows and bulldozer blades to the front of M-60 tanks.

"The manpower came from wherever they could grab them," said Smith, whose original team included a cook, a welder, two heavy-equipment operators and a group of Marines usually assigned to rounding up drunken sailors on shore leave and returning them to their ships.

But in two months, they have trained and equipped potent mine-breaching teams armed with line-charges that will be fired to detonate mines and create lanes through them.

Smith, a medical technician in a Baltimore hospital before he was summoned to active duty late last year, has dubbed his M-80 mine-scooper "Genesis" -- as in "the beginning, the first one through." Genesis has become home to a tight-knit crew of four.

The team members have begun hoarding food -- military issue as well as cans of fruit juice, loaves of bread, cookies, sugar and canned meats. It is enough food, according to the crew, to feed the four for a month if supply lines are cut.

What they don't need to eat they plan to use for barter. Because their unit has been culled from several others and finds itself at the bottom of most equipment-requisition lists, its members have refined their trading skills. They swapped an ice cooler for the wrenches needed to fix the tank, and they gave one of their tool boxes in return for batteries.

"We've had to fight for everything," Smith said. "We almost stole the tanks off the ships in order to get them."

It is the camaraderie forged among these fighting men that helps drive them during the long hours of waiting through cold, damp nights and hot, windy days.

"If we can't do our job, no one else can," said Mitchell, referring to the tanks and infantry that will follow his unit into battle.

Many of the Marines have turned to religion, superstition and good luck charms to give them the mental boost to face those jobs.

Cpl. Robert Stacy, 23, of New York City, has clipped two large safety pins in a crude cross on the front of his desert-tan Marine hat: "It is a sign of the cross -- or I can use it to fix my clothes when things start getting ripped up."

The crew of an amphibious personnel carrier dubbed "Blaze of Glory" has strung a plastic Bart Simpson doll on a string between two rear antennae. A tape of "Bart Sings the Blues" blares from inside.

For Mitchell, who joined the Marine Corps almost two years ago to escape his Northwest D.C. neighborhood and travel the world, his greatest fantasy now is returning to his hometown for a bar-hopping spree through Georgetown and a welcome-home parade down Pennsylvania Avenue.

He rubbed the cross his mom mailed him -- a nickel with a cross cut into its center. "With this, I can't go wrong."