The battle begins in the utter darkness between moonset and the moment when the first hint of a new day seeps into the east. More than 1,000 Soviet troops, riding scores of tanks, armored personnel carriers, howitzers and antiaircraft guns, rumble through Red Pass into the valley where the Americans are sleeping.

At precisely 4 a.m., the artillery opens up with a roar. The first salvos are nerve gas -- simulated with tear gas -- and the Soviet regiment slips into long-snouted gas masks. Fifteen minutes later, the valley is plastered with high explosive blanks.

By sunrise at 5:38 a.m., the Soviets have split into three columns, each hidden beneath a low fog of dust. One column veers to the south, another goes north, and the third waits in reserve. The Soviets believe the Americans want them to attack along the north wall of the valley; consequently, the northern column will feint in that direction before swerving south to join in a massive blow past a hill known as "the Peanut."

The columns, which had been traveling single file, spread into a broad assault front. A voice barks, "Execute Thunder," on the Soviet radios. Frequencies are switched to thwart American jamming and the attack force -- 170 vehicles strong -- charges west at full speed.

Twenty miles west, Capt. Bob Troxel squints into the night sight of his M1 Abrams tank. He has told his company to don gas masks and protective suits, for he knows the Red Army will be upon them soon.

For Troxel and his comrades in the 2nd Brigade, 1st Cavalry Division, this is Day 9 of war. Nine days since they moved out from their home base at Fort Hood, Tex.; nine days without a full night's sleep; nine days since Troxel, a 28-year-old New Jersey native now coated in desert grime, has taken a shower.

This is, in short, business as usual at the U.S. Army's National Training Center (NTC), a high-technology showcase set in 1,000 square miles of Mojave Desert moonscape with terrain features bearing nicknames such as "Afghanistan" and "Valley of Death."

Fourteen brigades each year travel to the desert base for what the Army says is the most realistic preparation for war, short of war itself: all-out tank and helicopter battles against a regiment trained in Soviet tactics, wearing Warsaw Pact uniforms and driving captured Soviet vehicles.

"Five years ago, people told war stories about Vietnam," said Col. Lory Johnson Jr., a senior NTC trainer for the past 18 months. "Now when they tell war stories, it's about NTC."

Troxel knows that the "Opfor" -- the Soviet-style opposing force -- often makes hash of the Army brigades at Fort Irwin. The 1,500 Opfor soldiers live here fulltime and know the terrain, the tactics, the tricks; Troxel would not be the first young commander to leave the desert a bit less cocky than when he arrived.

Under World War II tactics, the average tank battalion had to defend a sector of about 4,000 acres. Today, the increased firepower and mobility of modern weapons mean that the same size battalion must control about 83,000 acres to keep an enemy neutralized.

The Army knows it can't replicate war, even here. With nuclear weapons and long-range missiles excluded from these battles, the troops in some ways prepare to fight World War III by replaying World War II battles. They practice the Army's favorite "Big War" scenario, not the Vietnams and Grenadas that have perplexed the Army in recent decades. The barren ridges and dusty plains here couldn't contrast more sharply with the marshes, woods and rivers of central Europe, where the Pentagon expects the next big war.

And instead of bullets and tank rounds, both sides here fire smoke- and noise-generating blanks. "There's absolutely no way you can simulate blood and guts inside a tank," Johnson said. To gauge marksmanship and "kills," each weapon is equipped with a harmless laser, while every vehicle and soldier wear laser receivers that trigger a flashing light and an annoying beep when "killed."

For all that, a battle at NTC is more than a game, the soldiers say. The lessons learned in the stress, exhaustion and confusion of an NTC battle, they say, can be applied to an enemy in any climate. And the Opfor is a serious opponent.

"If this is not the best Russian regiment in the world," Johnson said, "we're in real trouble."

Code Word, Countersign

At 5 p.m. on May 20, the day before the tank battle, the Soviet attack plan is codified in Order 9869. In a hidden ravine near Red Pass, two dozen Soviet officers huddle beneath a camouflaged canopy for a final briefing.

For nearly an hour they listen to reports from the regiment's artillery, air support and operations officers. The battle objective is a distinctive rock outcropping called "Black Basalt" about 18 miles west of Lima Delta, the "line of departure" for the attack. The nitty-gritty of battle plans are reviewed, from the code word "Deerfly" and countersign "Shortcake" to the day's expected high temperature.

Virtually everything the Soviets know about the U.S. 1st Cavalry Division awaiting them in the valley comes from scouts who have been prowling the desert mountains since the previous night, infiltrating up to 10 miles behind the American lines on foot or in Soviet personnel carriers called "BMPs."

The reconnaissance platoon is run by Staff Sgt. Donald Garrett, a stocky redhead with a buxom mermaid tattooed on his left arm. Although the scouts sometimes can stroll through an entire company of sleeping Americans, today two of Garrett's men have been killed by sharp-eyed U.S. tankers. Three others are still hidden behind the lines and another squad is ready to go out at 6 p.m. for what they jokingly call "a night at the Coyote Club."

Remarkably, the scouts have pinpointed 43 of the 44 American tanks. Many are in the southern part of the valley, and the Soviet intelligence captain recommends angling the attack to the north.

But the last word belongs to Lt. Col. Bill Janes, the Soviets' regimental commander, and he decides to go south. Janes is tall, lean and sunburned. He wears a red star on his black beret; his fatigue sleeves are rolled up to the bicep and his forearms are cross-hatched with red, green and blue ink from leaning on maps all afternoon.

During two years as the Soviet commander, Janes has won more battles than he has lost and is considered a superb tanker. But the 1st Cav has him plainly worried. The enemy is well entrenched with new M1 tanks and new M2 Bradley fighting vehicles, which are fast, lethal and have excellent night vision scopes. "When those boys come to town," he mused, "they always cause me trouble."

"This is the largest tank force that we've fought," Janes said to his officers. "It's gonna be a close-in fight. Should be an interesting day. Any questions on my concept?"

There are no questions, but the strategy is controversial. Some officers believe the regiment would fight better to the north, where there's more room to maneuver. After some mild grumbling, the officers scatter through the ravine to eat, distribute ammo and perhaps catch 40 winks before the war.

Emulating Soviet Tactics

As the Americans steel themselves to the west, and as he surveys his company digging in for battle, Troxel is studious, almost grim. Some of his troops are stringing concertina wire across a key pass between Hill 876 and the Peanut, while an M1 tank, with several red skull-and-crossbones patches on its side commemorating past kills, raises a cloud of dust as it backs and fills into a sheltered depression on the valley floor.

Troxel said he knows the Soviets will try to punch through his defenses at the least defended point. Fort Irwin's Soviet soldiers don't drink vodka or read Lenin, but they emulate what U.S. intelligence officials believe Soviet tactics to be; and those tactics are predictable, rigid, "a setpiece of doctrine," Troxel maintains.

"We read their doctrinal manuals, and they read ours," he said. He paraphrases the Chinese philosopher of war Sun Tzu: "Know your enemy, know yourself."

Still, Troxel doesn't know precisely where the Soviet strike will occur, so with 10 tanks and four M2s he must defend the middle belt of a five-mile-wide valley. A few tanks will hug the northern slope of Hill 876, facing north; a few more will hide in "keyholes" along the southern ridge.

"We'll be trying to grill-door 'em as they go by," Troxel said, referring to the tanker's dream of shooting into an enemy tank's vulnerable rear end.

Elsewhere in the valley, two other companies, Delta and Foxtrot, are digging in to the east while Bravo Company will make a goal-line stand at Black Basalt to the west.

That leaves Troxel's Alpha Company to plug the middle. As the Soviets' Col. Janes suspects, the Americans hope the mines and barriers across the southern passes will encourage the enemy to go north, where Alpha's tanks will have a clearer shot.

"I need to kill a battalion at a minimum," Troxel said. "With my 14, I need to kill 40 to 50 vehicles."

Button Up the Tanks

Long before the Soviet tanks appear, the fighting begins for Alpha Company. Second Lt. Patrick Knapp, one of Troxel's platoon leaders, finds his tanks and Bradleys surrounded by Soviet infantry who have infiltrated during the night.

Knapp can see them through his thermal night-sight better than they can see him, but they are far nimbler than his heavy vehicles. When Knapp's .50-cal. machine guns jam, he is left with only M16 rifles to counter the enemy. So he orders his crews to "button up" by closing their hatches before calling in friendly artillery on his own position. The Soviets are wiped out.

Snatches of radio conversation drifting through the cold desert air make clear that infiltrators have been busy throughout the valley. It is clear, too, that no one in the 1st Cav is certain who has won the stealthy battle of the darkness.

"One BMP, at least one, penetrated our position last night, and I think they're to my rear," one platoon leader said.

"If you didn't turn on your thermal sights 'til midnight, you were too late, because they started moving at 2130," his commander responded.

"We had them on, but we were looking in the wrong direction."

Shots Fill the Valley

"Blue air! Blue air! Blue air!" The warning comes over the Soviet radio frequency at 5:56 a.m. and suddenly a pair of American A10 attack planes swoop gracefully over the southern ridge, dropping green flares to symbolize strafing runs on the Soviet tanks.

Twenty minutes into the tank battle, muzzle flashes fill the valley like fireflies. Crippled American M1 and Soviet T72 tanks begin to stack up in "parking lots," their yellow beacons flashing to signify death.

Soviet vehicle 006, commanded by the regiment's executive officer, Maj. Dave Murdock, is in the attack's southern column. At 6:13 a.m., Murdock's gunner fires a missile at an M1 on Hill 780 a mile to the northwest; when the beacon flashes, Murdock yells, "You got him! He's blinkin'! Good shooting!"

What Murdock does not know, given the dust and smoke and confusion that comprise the fog of war, is that the Soviet northern column, commanded by Capt. Donald O. Grimm Jr., is being massacred. An American tank company and minefield, undetected by the Soviet scouts, is perfectly dug in along the northern ridge to prevent Grimm's column from swinging south as planned; at 5:52 a.m., an M1 tank is destroyed, but in the next few minutes, as Grimm would later recall, "it turned into a melee. Got punched out pretty quick."

With that, the die is cast and the battle lost. The southern column, although reinforced by the reserve battalion, is too weak to overwhelm the swarming M1s. American Cobra helcopter gunships begin raking the Soviets from the rear. Efforts to take a detour to the south through Hidden Valley are repulsed by a deep antitank ditch across the valley's mouth.

Janes' distinctive high-pitched voice can be heard over the radio, asking the whereabouts of "Ivan," code for the Soviet attack planes. In fact, mechanical troubles have forced Ivan back to the airfield. When the Soviet jets finally arrive, in the form of two F16s, the bombing runs are too late to make a difference.

At 6:30 a.m., Murdock arrives at the Peanut, which sits in the middle of the valley in the southern shadow of Hill 876. The American minefield and concertina wire barricade have turned into a "kill sack," where five Soviet tanks and and six armored personnel carriers are trapped like flies in a spider's web.

Janes' voice on the radio is increasingly alarmed. "Watch your right flank. There's a lot of repositioning to the north." As if on cue, several M1s appear from behind Hill 876, racing to the west to intercept the surviving Soviets. The attack is beginning to assume the ambiance of George Armstrong Custer and the Battle of the Little Big Horn.

Murdock's 006 and another Soviet tank halt to swap shots with a pair of M1s about 1,000 yards to the north. When the yellow strobe atop the other Soviet turret begins to flash, Murdock retreats in a desperate search for a hiding place in the wadis. But it's too late. At 6:47 a.m., 006 is hit and the electronic sensors flash the fatal message to Murdock and his Soviet crew: Signal 12, destroyed by an M1.

Murdock and his crew remove their helmets. The front slope of the hull is littered with chewed up sunflower seeds where the driver nervously spit them during the battle. The gunner, squatting on the turret, opens a cold can of Campbell's pork and beans and drinks it for breakfast. Murdock wonders aloud whether he should have tried to run instead of hide. At 7:13 a.m., the umpires declare the battle over.

Tanks Breach Barriers

From the arroyo "keyhole" where Troxel has backed his tank, most of the battle is obscured. As dawn broke, he could see a frightening cloud of smoke and dust boiling above the advancing Soviets.

"What you need to do right now," the U.S. commander says over the radio, "is shoot straight."

About 30 minutes into the battle, the war suddenly blows into Alpha Company's front yard. "They're through, they're through," Troxel hears, as the first Soviet tanks breach his barriers.

Troxel's tank and a half-dozen others on both sides of the pass open fire. Three glorious minutes later comes a more welcome report: "They're getting stacked up in the minefield."

Troxel's battle is over almost as soon as it begins. As he takes aim at a Soviet T72 and a BMP trundling up his wadi, he is hit from the rear.

"I felt like Custer there for a minute," Troxel said. "I turned around and there was tank, tank, tank behind me."

His tank dies 300 yards east of where Murdock's 006 was hit. But Troxel and his Alpha Company have done their job: 33 Soviet tanks and infantry carriers litter the pass between Hill 876 and the southern ridge.

In a real war, of course, the young captain and most of his men would be dead or injured. Only two tanks and one Bradley of his original 14 have survived.

And Troxel knows, too, that in a real war the first Soviet regiment would be followed by successive waves. At West Point, future officers learn that the Soviets have 52,600 tanks.

"The Russians outnumber us, and they tend to be a little more liberal with their casualties," Troxel said. "He can take 80 percent losses in one regiment, punch three more through, and he's succeeded.

"Of course, that's not very good news for the first regiment."

At 8:20 a.m., the resurrected Soviet officers gather on the desert floor to ponder their losses. The attackers began with 40 tanks and 94 armored personnel carriers; less than two hours later, they are left with three tanks and six BMPs. The 1st Cav has 14 of 38 M1s left and five of 14 Bradleys.

Janes was one of the few Soviets to make it to the Black Basalt before being killed. (One Army major would later observe: "When the regimental commander is out in front leading the attack, you know you're in trouble.") Janes ponders his strategy and decides that although it was the correct plan, it was doomed by the undetected nest of M1 tanks to the north.

"I've got no major heartache," he tells his officers. "You guys executed the plan I put on the ground."

And he is full of praise for the American defense, particularly their M1 tanks and Bradley fighting vehicles. "What you saw here today is evidence of what they can do. I don't like fighting these guys. If used properly, they're devastating. Today they were used properly. My Soviet regiment is in the dust."