That will change. Some frontline grunts will lose their enthusiasm when the cold Bora winds blow in off the Adriatic and chill them to the bone. Others will rethink the mission when the first sniper bullet cracks overhead. Still others won’t change their minds until there is an actual “incident”: a buddy catches a bullet or steps on a land mine and turns into a body bag full of mangled flesh. Then the troops will demand to know what the hell they’re doing there, what fool sent them and when they can go home. So will their relatives, friends and congressmen.

As I packed my gear last week for another trip to Bosnia, the memory of the first dead soldier I ever saw suddenly flashed in my head. It happened 50 years ago, when I was a fresh recruit in my midteens. And it happened only a few hundred miles from Tuzla, the Bosnian town where 20,000 Americans are now scheduled to deploy. My unit, the 351st Infantry Regiment, was dug in along a demilitarized zone called the Morgan Line. Our job was to keep Tito’s Yugoslav partisans out of the Italian-controlled city of Trieste, which they figured was a prize they had earned in World War II by fighting the Germans to a standstill. We weren’t officially at war with the partisans, but they resented our presence, so they made things hot for us by sniping at our positions, shooting at our aircraft, ambushing our patrols and scattering mines and booby traps along the paths and roads we used. The dead young army captain had stepped on one of them. I can still see his hair stirring in the breeze and the bloody stumps where his legs had been.

He wasn’t the first or last American to die there. Dozens of airmen and grunts would be killed, captured or wounded along the Italian-Yugoslav front between 1945 and 1954 in a conflict that few Americans know about. The brass told us it would be a one-year mission, not unlike Clinton’s Bosnia plan, but it took nine years before a final deal was cut and the regiment came home. That was where I got my baptism of fire and where I learned that the Serb, Croat and Muslim soldiers in the partisan army included some of the meanest fighting men on earth. The crazies I fought there still take the prize as the most vicious and hard-core extremists I’ve bumped into in the 12 wars I’ve experienced as a soldier or correspondent.

The all-volunteer U.S. Army is the most professional force this country has ever fielded. It has every tool it needs to do the job in Bosnia. But despite all the gold-plated, stealthy technology that makes things faster and more lethal, warfare hasn’t changed much out at the pointy end of the spear, where the grunt tries to stay alive. It’s still a dirty game of kill or be killed, and the critical governing factors–terrain, weather and the enemy–are as absolute as they were at the battle of Jericho.

Mountainous Bosnia is a cross between Germany’s Hurtgen Forest and Vietnam’s Central Highlands, scenes of some of the bloodiest fighting in two previous wars. The terrain is steep and heavily timbered, with treacherously narrow and muddy roads and mined or damaged bridges. It is a tightly compartmented landscape, where a patrol can easily get trapped and cut to pieces. The ground is strewn with literally millions of uncharted mines and booby traps, usually covered with snow at this time of year. In Vietnam, 60 percent of all U.S. casualties came from these terrible devices, which not only took lives and limbs but also gutted American morale. The mines used today are even worse; many are made mostly of plastic and thus can’t be picked up by metal detectors. Gen. Dennis Reimer, the army chief of staff, tells me how these mines have to be found: “With a bayonet.” Like their great-grandfathers in World War I, the warriors of IFOR will be down on their hands and knees with bayonets, probing and praying.

The army plans to go into Bosnia with a “heavy” force of tanks and armored personnel carriers, most of them provided by the First Armored Division, now based in Germany. That sounds awesome to the laptop commandos in the Pentagon and other citizens not familiar with ground combat. The 70-ton M1-A2 Abrams tank and the 30-ton Bradley fighting vehicle will be the major players. Both proved formidable in the Iraqi desert, but Bosnia, as the Germans found out in World War II, is not tank country.

Last August a lightly armored United Nations vehicle skidded off a wet mountain road and tumbled down a draw, killing three U.S. envoys. That vehicle weighed only half as much as a Bradley. “Right now, the terrain there is a no-go for armor,” says an army tank colonel. “Most of the heavy stuff will sit in tank parks until the bridges and roads can be repaired, which will take months. Most of the roads and 95 percent of the bridges won’t take an Abrams or a Bradley.” The chairman of the Joint Chiefs of Staff, Gen. John Shalikashvili, promised Congress the U.S. force will be “robust.” But without usable armor, American troops in Bosnia won’t be much better off than my light infantry regiment was in those same mountains 50 years ago.

Our troopers are scheduled to go in December, the worst possible time in terms of snow, ice and numbing cold. Frostbite will be a big problem for the Joes and Janes up front, because on the forward edge, along the DMZs, there will be no warm tents such as those enjoyed by the REMFs (“rear-echelon misfits,” you might say). Our grunts will hunker down in cold foxholes and bunkers, just as their forefathers did from Valley Forge to Korea, staring out into an icy no man’s land between the warring factions and trying to keep their fingers and toes from turning black.

Icy roads and snowdrifts will be nightmares for American drivers. In the gulf war, road accidents were the biggest cause of American casualties; in Bosnia it could be even worse. And winter weather also brings heavy cloud cover, low ceilings and ground fog, limiting the use of American air power, which is a major component of Shalikashvili’s “robust” force. “If a fighter aircraft or an Apache chopper pilot can’t see the target, they ain’t exactly going to be robust,” says Dale LeClerc, a Vietnam-era helicopter pilot with more than 400 combat missions.

This mission won’t be easy; Bosnia is no Haiti. As in Vietnam, it will be hard to tell the bad guys from the worse guys, and weapons will be everywhere. The combatants are seasoned veterans who have learned plenty of nasty tricks during 43 months of self-imposed holocaust–and centuries of hatred. All three Bosnian factions have some diehard fruitcakes who won’t accept what went down in Dayton, no matter what their leaders say. They might revert to guerrilla warfare, or they might lie low and wait out the U.S. occupation, starting up the horror show again when we’ve left. Serb extremists may seek revenge against our troops for the U.S.-led NATO air attacks that pummeled them for weeks and forced their leaders to the peace table. Bosnian government extremists may shoot our forces in the back, blaming the Serbs and hoping to enhance the Bosnians’ image as victims.

Our own behavior will stir up further enmity. The 10th U.S. Special Forces Group, based in Fort Carson, Colo., will be responsible for training Bosnian government troops. The Serbs (and possibly the Croats, too) will rightly conclude that we have taken sides, which is the ultimate sin for peacekeepers. “We won’t be exactly neutral,” snorts a Green Beret captain who is scheduled to go in with the first wave to train the Bosnian Army. It’s an impossible task: keeping a peace that not everyone wants and at the same time training one of the combatants. That’s what we tried to do in Lebanon in 1988, and the result was the suicide bombing at the Marine barracks in Beirut, in which 241 of our troops died.

If any of the balkan combatants decide to oppose us, they won’t draw a line in a muddy valley or slug it out toe-to-toe on a hilltop. They know that in this type of fighting, Americans are best, and best equipped. The Balkan fighters watched TV and saw what happened to the Iraqi Army. Instead, their MO will be the Somali model: nickel-and-dime, ankle-biter stuff that produces lots of blood and body bags for the TV cameras. Their tactics will be the same ones used by Yugoslav partisans to hold off the Germans: hit-and-run raids, mines and booby traps, mortar and terrorist attacks and selective sniping.

Some of the military professionals I spoke to last week said I should add a fourth item to my list of governing factors. They called it “the threshold of pain,” and they meant it in a political sense, not a physical one. “If it comes to a shooting match, no one can slug it out with our forces and win,” said Colonel Hunt, the best serving combat leader I know. His fear is that “the commanders on the ground will again have their hands tied, and we will see a repeat of Vietnam.” No one expects a war on anything like the scale of Vietnam; the political decision has already been made to keep IFOR smaller than many of the military men would like. But the political interference and waffling may have a familiar ring to it. How many dead Americans will it take to force a premature withdrawal from Bosnia? No one knows, and I hope we’ll never find out.

With or without heavy casualties, the task ahead is difficult. After a long train ride from Germany, people in battle dress will have to convert the subtle language of pin-striped politicians and diplomats into something doable. They must take compromises that were deliberately fudged and translate them into concrete action. What do they do when a Muslim wants his house back, and the Serbian family occupying it refuses to leave? How do they respond when an American is hit by sniper fire from the direction of Serbian lines, but an informant reports that the shot was fired by a Bosnian Muslim? The challenges that await the grunts in Bosnia are the toughest the army has faced since Vietnam.