It's a beautiful day for a war. The frost on the ground at reveille has melted away under spotless skies. Except high in the mountains surrounding the valley, the snow vanished weeks ago. By 1000 hours, temperatures have climbed into the forties, and before the battle has ended in mid-afternoon, soldiers will be shedding helmets and overcoats in 60-degree heat, their arms and faces raised toward the ventilating breeze.

This is crazy weather for central Pennsylvania on the last weekend of January, and for the 900 or so military reenactors, gathered at Fort Indiantown Gap military base for their annual re-creation of the Battle of the Bulge, the balmy morning presents yet another "inauthentic" factor in their scenario of war, January 1945.

Fifty-seven years ago, in the Ardennes region of Belgium, the winter was not so kind. Cold took a horrific toll on both Allied and German armies at the Battle of the Bulge. Soldiers sank up to their waists in quagmires of snow. Roads were pitted with Olympic-size puddles, and passing tanks splattered icy mud on sleep-starved troops. Knifing winds froze toes and trigger fingers. Hundreds of men on both sides died from exposure or had limbs amputated.

Then again, military reenacting has always been more about fantasies of time travel than acknowledging the unpleasant facts of history. Given the million other things this day that won't begin to approximate the conflagration of World War II -- blanks instead of bullets, for starters -- a discrepancy of 50 degrees is comparatively minor and, for these mostly out-of-shape weekend warriors who will be humping rifles and packs up and down stony hillsides for hours, not unwelcome.

Every weekend somewhere in the United States, groups like this come together to dress up in WWII gear and fire off WWII weapons. Outfitted as GIs and Nazis, they assume roles on the world stage of 1939-1945, when governments killed more people in less time than ever before or since. Gruesome fascination with the period, especially the almost incomprehensible crimes of the Third Reich, has not diminished with time. The once-a-year gathering at Fort Indiantown Gap (known to insiders as the BOB at FIG) is the biggest event on the calendar -- the Super Bowl of WWII reenactments -- and enthusiasts from around the country prepare all year for the spectacle, which culminates in a large-scale battle.

The BOB at FIG is designed exclusively for the reenactors themselves, and they pay good money for the right to shoot at one another in the woods above the base. But as a public-spirited gesture, the organizers also stage a "tactical" down in the valley -- open to anyone. This year it matches Grossdeutschland, the most rigorous of all the WWII units and a showcase for what reenacting can be, with the more relaxed American members of K Company.

A man with a loudspeaker offers play-by-play analysis to about 200 of us who have gathered on a hillside overlooking a treeless plain. "The Germans have won the toss, and they will be attacking."

In jeeps and on foot, K Company moves swiftly across the field, then turns to confront its opponent. As Grossdeutschland slowly advances, a hand signal from a referee starts the battle. Volleys of blank rounds echo across the valley.

A German Hetzer (a light tank) opens up on the Americans; they return fire with a howitzer and a .30-caliber machine gun. Although the combatants are no more than 750 yards away, the crackle of rifles and the boom of cannon sound distant and toy-like. None of the spectators I can see have put down their coffee and hot dogs, served from a convenience truck, to cower in fear.

"Bunch of wannabes," mutters Bob Hyde, a 79-year-old who fought at the Bulge with the 109th Infantry, 28th Division. "All wars should be like this," he says with a wry smile. "No casualties."

Two years ago, during my first visit to the BOB, the war game was a wide-open affair. A friend and I drove freely around the training area of the base. Following the sound of gunfire up into the mountains, we ended up parked a dozen yards from an American battery with a 37mm howitzer that was shooting blank shells at unseen German placements. We chatted with the dead as they trudged out of the snowy forest, and several let us fire their carbines. An American reenactor asked if I wanted to join his unit as a war correspondent.

But post-September 11 security measures went into effect this year. With MPs checking ID at the entrance to the parking lots, and armed guards standing at intersections near the reenactment, the restrictions on journalists became far more severe -- just as in a real war these days. I tried to be thankful for the access I did receive. After all, it is strikingly generous and odd that for 12 years the U.S. military has rented out a base for a weekend gun battle. Some fear if Donald Rumsfeld knew about these shenanigans, it wouldn't go on much longer.

That would be a pity. Lasting four days, the event is well planned, and a bargain. Starting on Wednesday with the opening of the flea market, it peaks on Saturday with the "scenario." In between are mandatory classes on vehicle driver safety; meetings for role-playing medics, MPs, company commanders and overall commanders (Allied and Axis); and, this year, screenings of the HBO film "When Trumpets Fade." Everything winds up on Saturday night at the officers club with skits, songs and other "period entertainment." A fee of $37 (the no-meal plan) gives reenactors, U.S. military veterans or flea market vendors a bed in a barracks for four nights and access to all of the above.

Each side in the scenario is given an objective, time to set up troops and a limited supply of ammunition. Areas in the FIG woods are designated by overall commanders to represent famous sites in the Ardennes. This year the Americans were told to take "St. Vith" and to protect "Bastogne" in the rear, the Germans to achieve the reverse. The scenario changes annually, depending on how many units of which armies sign up to attend. Americans and British turned out in force this year. Two years ago the Germans ruled. (In the battle they took their objective in 45 minutes, crushing the Allies so quickly that the reenactment was reenacted. "They cried and whined," an SS captain told me in disgust. So the Germans caved in and were trounced the second time.)

Brawls have broken out over "kills." Angry cries of "I dispute that hit, pal" are commonly heard when fighting with blanks, although most reenactors confess that "you know when someone's scored a good hit." The dead simply walk off the battlefield and wait for the living to finish.

At 1500 hours the war is whistled to a close.

It's a thankless (and nonpaying) job to keep 900 grown men excited for an afternoon: to compress six weeks into five hours, a 100-mile front into 41/2 kilometers, and plan for a fair fight, knowing there may be a force ratio of 2 to 1 in favor of one side or the other.

William Bethke, a 47-year-old U.S. Navy veteran who works for Boeing in Chantilly, was commander of Allied forces this year as a British brigadier. He has reenacted since 1981, playing a British soldier in the Revolutionary War, a Confederate in the Civil War, and, since 1984, a British commander in World War II. He likes to stress his hobby's positive message. "If you can touch and feel something, you can

better understand it," he says. His wife takes part, too, as an English or Welsh participant.

The trappings of power at the BOB reenactment are nothing to speak of. Bethke pays for some necessities -- photocopying terrain maps and mailing them to commanders in the fall -- out of his own pocket. On the walls of the barracks that constitute Allied headquarters hangs a small poster of Winston Churchill and an aerial view of the FIG base. An old typewriter and a disconnected '40s-era phone sit on a desk. (Chief organizer David Shaw rents the FIG base for $60,000 from money collected through dues paid to the World War II Historical Preservation Federation, and from attendees. Any money left over is rolled over to the following year.)

Bethke is aware of the event's unusual status -- "This is the only base on the East Coast that allows civilians to come and play in their sandbox," he says -- and claims the hardest part of his job is getting people to cooperate. "We have some bad officers, some bad sergeants," he says with a sigh. "They don't want to follow orders. All they want to do is fire a gun. Okay. That's fine. I enjoy that, too. But this base has security concerns. We're allowed to be here because of our reputation. Five or six years ago we were known as a loose organization. We have to be stricter now about rules and discipline in part because this isn't the same place it was on September 10th."

Everyone scheduled to fight must submit to a safety and authenticity inspection at 7:30 on Saturday morning. But when we pull in about the same time, things are behind schedule. In the area behind the garages and in front of the firing range where the armies are supposed to muster, ranks are ragged with the missing. An American squad is practice-marching along the lanes between the barracks ("one, two, three, four/I don't want to go to war"), and all over the parking lot late-risers are pulling weapons and winter gear out of car trunks and minivans.

Outside of a Spielberg production, you're not likely to see a finer collection of WWII uniforms and hardware. Trained units of American, German, British, Rus-sian and Canadian reenactors typically turn up. Owners of jeeps and trucks from the period, many of whom belong to the Military Vehicle Preservation Association, drive from as far away as Utah and California. Heavy armor is shipped to the base by rail or semi. The event may be the only opportunity for collectors to show off restored materiel or recent purchases in front of a discerning audience.

Much to everyone's disappointment, no heavy armor has made the trip this year. Sherman tanks, a common sight at previous BOBs, are a no-show. Reenactment veterans speak nostalgically of the late '90s as the heyday at FIG. Enough tanks were on hand in 1996 for them to have a small battle of their own. But the man who owned two panzers had to sell them (one for $250,000) to pay for a divorce. Or so goes the story.

Even so, lining up for review and spewing plumes of frosty diesel smoke are an array of German machines: several '40s BMW motorcycles with sidecars, a 1943 Ford truck (manufactured in Germany), a 1943 and a 1944 Kuebelwagen (a scout car), and an eight-wheeled light armored infantry support vehicle in a period reproduction from Florida.

The popularity of WWII reenacting and WWII movies has spawned cottage industries that produce everything from uniforms to firearms to blanks to insignia. For original German items, the Balkans has become a favorite hunting ground.

Americans tend to be overshadowed by Nazis at the BOB. German industrial design and haberdashery cut a more intriguing shape, with more chiseled lines, than American counterparts during the '40s. Had the war been fought and decided on issues of style rather than ideology, the Germans probably should have won.

The curiosity this year is a restored Schwimmwagen. One of the first amphibious vehicles, originally made by Volkswagen, it is owned by Dale Taylor, 47, of Columbus, Ohio. He bought the Schwimmwagen from a scrap metal dealer in Belgium for $31,000 and spent $30,000 on the restoration. A marvel of engineering, it will do 8 knots in the water, has a steering wheel on either end and four-wheel drive. Of 14,267 made, fewer than 100 still exist.

Sitting inside the open cab with his buddy Rick Pemberton, 54, both caparisoned in goggles and camouflage, Taylor poses for photographers with a jaunty air and a smile. As reenactors since the early '80s with the 1st SS -- Hitler's bodyguards, who surrendered in 1945 in Austria -- both men are proud to belong, in Taylor's words, to "a kick-ass unit that was manned by all the best Waffen conscripts."

Both men also insist on their distance from aspects of the originals they portray. "A lot of people misinterpret what we do," says Pemberton, who spent 28 years with the National Guard and now works full time as a Blackhawk helicopter flight instructor. "We reenact Germans with an understanding of the atrocities and the stigma and all that. We don't do parades. We don't fly the flags. What we do has nothing to do with politics."

There are multiple-personality reenactors who play Allied or Axis depending on the needs of the scenario or their mood that day. But most choose a particular character to be, sometimes based on a WWII identity card they have found. The hope is to deepen their impression each time they dress up and fight. It's not unlike Method acting.

White males predominate in military reenacting, and WWII is no exception. Black and Asian faces are rare among the troops. Fewer than 25 percent of the BOB reenactors served in the military, and only about 10 percent have combat experience. A group of women called the Paper Dolls -- founded in 1999 to recognize the range of women's roles in WWII, from nurses to WACs, USO hostesses to Rosie the Riveter -- attended this year. They are serious but undogmatic about the creed of authenticity. Kate Krause, one of the founders, sneers at the "bogus" '40s hairstyles in the movie "Pearl Harbor." But she also holds to what she calls the "10-foot rule": If an impression is credible from 10 feet away, that's okay. Obsessive, thread-counting reenactors she dismisses as "stitch Nazis."

For many, the BOB at FIG is also a chance to star, or at least be an extra, in their own WWII movie. When asked why they return to refight the Battle of the Bulge every year, their first response is usually: "To honor the veterans who gave their lives to preserve freedom." But most admit to less patriotic, more complicated motives as well. "I can disappear into a character for a weekend," says a Massachusetts man in charge of a German panzer division. "I can command these men. This is my acting career."

The ultimate goal for many here is to vanish into a role so that one temporarily loses track of time and place. These "magic moments," as a German reenactor calls them, are precious and can't be planned for. "You're lying there and all around you guns are going off in the fog. The light is just right and you look around and suddenly you're lost. For about 30 or 40 seconds you're transported. You think you could be back there fighting in the war. It's kind of creepy but fulfilling."

If these men were merely would-be movie stars, however, and their war games innocent make-believe, many of those dressed as Nazis would not be so nervous about my using their names. "My co-workers wouldn't get it," says a CEO from New Jersey who portrays an SS officer. For some of these men to don a Nazi uniform is to experience the illicit thrill of thumbing their nose and clicking their heels at American morality; they're touching evil. "It's the ultimate transgression," one tells me.

The organizers prohibit any public display of the swastika. But in one area of the flea market I notice a table cloaked in a Nazi banner that appears to violate the rule. The proprietor is nowhere in sight. His sale items are mainly books about the Third Reich, including one titled Gun Control in Germany 1928-1945 by William L. Pierce, author of The Turner Diaries, the anti-Semitic, anti-black, anti-government novel that inspired Timothy McVeigh.

Another vendor in an FDNY baseball cap sees me flipping through the book and offers to help secure the sale. Nearby, his own table and the wall behind it proffer row upon row of Nazi posters and CDs in low-grade reproductions. There is everything here, from a collection of Hitler's speeches to SS marching songs.

When I tell him I'm reporting a story about WWII reenactors for The Washington Post, he grows visibly wary. "Is that a liberal paper?" he wants to know. I tell him some have classified it as such. "Then you're the enemy," he announces. I'm not sure what he means. "Should people be accountable for their own actions?" he asks. I tell him, yes, of course, they should. "Don't you think there are too many social programs?" he says. I shrug. Anxious to end the interview, he demands my tape recorder be turned off. Unappeased when I show that it is, he grabs back his business card.

Bethke acknowledges that a few neo-Nazis may have crept into the hobby. Organizers don't run security checks or take Social Security numbers.

"Do we have extreme political views in World War II reenacting?" he asks rhetorically. "Yes, we do. But the percentage is probably one-tenth of 1 percent. Those people we do not like. We know who they are. They put the impression of a soldier in a bad light. The 'Germans' are not unwelcome. But this base has put in some specific instructions. People have to obey those rules or they won't be invited back."

Whether a more orderly BOB would ruin the chaotic fun of reenacting here is a lively and unsettled question. More than one reenactor this year recalls BOBs "five or six years ago" fondly. Those events included tank battles as well as some of the more macabre aspects of the original horror, such as the massacre of American prisoners of war by their German captors at Malmedy. "I had the pleasant task of going around to each guy on the ground and capping him with my pistol," an SS soldier tells me with pride.

Web sites for all the German reenactment units contain warnings that neo-Nazis need not apply. The disclaimer for Grossdeutschland is typical and reads: "Our main purpose is to research and present the common German soldier as accurately and objectively as possible. We must stress 'objectively' -- we concentrate on the military aspects of the soldier. We DO NOT support or in any way condone the politics which directed him."

Bob Lawrence, a 47-year-old electronics executive from Long Island, is the captain of Grossdeutschland. Two years ago I visited him in the unit barracks, which is guarded 24 hours a day by an armed and uniformed sentry. In a separate room in back, where he displayed toiletries of the period as well as a Berlin transit map from the '40s, he outlined the precautions his unit takes.

"There are some people who want to join for torchlight parades and speeches. I tell them, that's not us. We tolerate no crazies. Everyone who joins has a year's probation so that we can make sure you're serious in the ways we're serious."

Hugely proud of his men's desire to immerse themselves in the roles they play -- all members must understand select commands in German -- he spoke with tears in his eyes about a trip to Germany in 1999 when Grossdeutschland reenactors met surviving soldiers of the original army they impersonate.

"In their own country, they're criminals," exclaimed Lawrence. "They haven't been able to talk to anyone but each other for 60 years!" Since returning, the membership has stayed in touch with German veterans and invited them to witness the BOB at FIG as well as other events.

Grossdeutschland takes WWII reenacting about as far as it can go before it turns sinister. And perhaps the unit skirts the edge. Any effort to divorce Germany's military from Hitler's ideology, the Nazi war machine from the Holocaust, is inherently problematic. It also runs counter to any quest for authenticity. Hitler's politics saturated everything in Germany, including his armies.

Events like the BOB take place in several countries on a smaller scale, from Australia to Russia and Britain. But the firing of guns, even with blanks, is illegal in most other reenactments. According to Lawrence, "In the U.K. they have to run around and pretend to shoot each other with their hands, like when you were kids: 'Bang, you're dead.' "

Second Amendment politics, as much as love of history, seems to explain the appeal of the BOB for many attendees. Shooting one another with fake ammunition and real guns is a protected American right that more than a few here hold precious. They wait all year for the chance the weekend affords to fire a machine gun legally (with the proper paperwork).

No other country would allow civilians to play war so seriously, on this scale, and it's hard not to be a little bit proud that such dangerous nuttiness is tolerated. Most of those I have spoken to at the BOB seem united by a love of freedom and lethal weaponry along with a burning hatred for Bill Clinton.

A U.S. reenactor had a clear perspective on the BOB's appeal: "This event is one-third about history," he said, "and two-thirds about burning powder."

Saturday night at the officers club, the main social event of the weekend, can be a rowdy affair. The battle may be over, but everyone seems reluctant just yet to step back into their workaday roles. The night affords an opportunity to stay in character and look your snappiest. Both men and women take their pricey dress uniforms out of mothballs. Bethke attends in his Welsh Guards "scarlets," which include pants, tunic, ceremonial sash, bearskin and boots. Such magnificence cost him $3,000.

Two years ago, as the centerpiece, the Allied and Axis forces traded insulting songs about each other, British lyrics being by far the funniest and filthiest. This year is sweeter, more in the spirit of a USO show than a beery shouting match. A 17-piece swing band plays "Bye Bye Blackbird," "I've Got You Under My Skin" and other popular songs of the era. GIs lindy-hop with the Wehrmacht. Amateurs step forward to do comedy skits or croon sentimental ballads. An American ensemble stands shoulder to shoulder to sing an original satire called "The Day the Fuehrer Died." The Paper Dolls dance with soldiers of all nations.

The party continues back at the barracks, where several groups have pitched in to buy kegs. On the porch at the Grossdeutschland barracks, where the sentry is now off duty, Bob Lawrence hoists a beer stein and joins a pair of strolling accordionists in singing "Lili Marlene." I talk with a first-timer from France, where dressing as a Nazi is illegal. He bemoans the "messy chaos" of the day's battle, an opinion shared by many at the barracks, unhappy with the outcome of the scenario. (This year the Allies won handily.)

But two years ago, at about this same time on Saturday night, an incident took place that rattled many of those who portray Germans for kicks. A young man appeared at one of their barracks with a canister marked Zyklon-B, the cyanide pellets used in the gas chambers of the extermination camps. No one was sure if the contents were real or fake. In any event, the stranger was quickly set upon by several German reenactors. "This isn't what we're about!" one shouted. To which the man replied, not illogically, that he was only adding a note of authenticity.

Devoted to a vision of World War II as action picture and stripped of its annihilating politics, reenactors nonetheless seem more juvenile than dangerous. They're acting out the American war movies and television they grew up on in the '50s and '60s, war as gunplay and costume drama. If some of these men seem more than a little worried what the world will think of what they're doing in the woods on their weekends, maybe they should be. But maybe feeling embattled and not knowing entirely why they're there is half the thrill.

Richard B. Woodward is a writer and editor in New York.