CHÂTEL-CHÉHÉRY, France — On Oct. 8, 1918, Cpl. Alvin Cullum York and 16 other American doughboys stumbled upon more than a dozen German soldiers having breakfast in a boggy hollow here.
The ensuing firefight ended with the surrender of 132 Germans and won Corporal York a promotion to sergeant, the Medal of Honor and a place in America's pantheon of war heroes.
Now another battle is unfolding as rival researchers use global positioning systems and computer programs, old maps and military reports to try to establish the exact site of the fighting on that day 88 years ago. Their heated examinations do not challenge the essential heroism of Sergeant York, yet such scrutiny helps explain why it is hard to be a hero these days.
There are other reasons, too, of course. Wars are often unpopular clashes fraught with moral ambiguity, and while the news media are often attracted to heroism, they also like to challenge myth building.
The military's attempt to turn Pfc. Jessica Lynch into a hero after the invasion of Iraq unraveled when it emerged that she had not emptied her rifle at advancing Iraqi soldiers, as first reported. The initial accounts of Cpl. Pat Tillman's death in Afghanistan in April 2004 came undone when it was disclosed that the corporal, a former N.F.L. star, had been killed by members of his own unit.
Military abuses now have a longer shelf life than acts of derring-do.
It was easier to create heroic stories in 1918 when the press was more pliable and the public more gullible, and the popular media had a fondness for uplifting tales of uncomplicated bravery. Though newspaper articles at the time refer to members of Sergeant York's platoon who challenged the accounts of that day, the doubters were given only enough attention to dismiss them.
His exploits grew until he had single-handedly silenced 35 German machine gun nests and killed 25 enemy soldiers.
The latter-day search for the site of his heroic stand raises questions about the long-accepted story. In particular, evidence of the sprawl of German military positions that day does not mesh easily with the geographic concentration described in Sergeant York's published diary.
According to his account, he was in a group of 17 men who sneaked behind enemy lines to attack German machine gunners who were holding up a larger American advance. They surprised a group of soldiers, who surrendered, but almost immediately came under fire from machine gunners on a ridge 30 yards away.
Six of the Americans were killed and three others were wounded, leaving then Corporal York the officer in charge. He is credited with overcoming the superior force by using his sharpshooting skills, honed during turkey shoots and squirrel hunts in the Tennessee woods.
"Every time I seed a German I jes teched him off," his published diary reads.
This version holds that the senior German officer in charge eventually offered to order his men to surrender if Corporal York would stop shooting. Within weeks the young Tennessean was being feted as a war hero, and by the time he returned to a New York City ticker-tape parade the next May, he had been anointed the Great War's bravest patriot.
But even he seemed bemused by the mythmaking that surrounded him, and he shunned the lucrative limelight after the war for the obscurity of his old Tennessee home.
His heroism might have been forgotten outside the state had Hollywood not revived the story in the 1941 film "Sergeant York." Gary Cooper won an Oscar for his portrayal of the hero, and the film became the highest-grossing movie of the year as another European war was under way.
But underlying the well-shaped tale is a murkier, more complex narrative. Sergeant York's published diary is actually a heavily embellished account written for magazine serialization in the 1920's with help from a flamboyant Australian soldier-poet named Tom Skeyhill, who was blinded earlier in the war.
That diary contradicts itself on several points, and the homey, mountain vernacular in which it is written is almost certainly an invention of Mr. Skeyhill, who often wrote in colorful dialects. Michael Birdwell, a historian and the curator of Sergenat York's papers at the Alvin C. York Historic Site, says the sergeant's family has never made the real diary available to historians, so it is not clear what it contains.
"The question is, what is really York and what is after-the-fact addition and what is plain fabrication?" said Mr. Birdwell, who is part of a team searching for the exact location of the battle. "I personally dismiss much of the document."
Nor did Sergeant York's tale go unchallenged. Although the Army took affidavits from the surviving platoon members corroborating his account, at least one of the men later asserted that he, too, had fired his weapon during the battle and that it was impossible to tell who was responsible for killing the most Germans or how many of them had died.
Two corporals, William Cutting and Bernard Early, who were both wounded, said the Sergeant York legend had started with a reporter for The Saturday Evening Post, George Patullo. They met him at a first aid station after the incident, they said, and told him about the day's events.
Mr. Patullo chose to focus on Sergeant York, presumably because of the tighter, richer narrative his story allowed. The article, titled "The Second Elder Gives Battle" in a reference to his position in his Tennessee church, tells the story of an uneducated backwoods Christian who reluctantly goes to war and reconciles his religious beliefs with his sense of duty to his country.
The article made him an instant celebrity. But Corporal Cutting insisted long after the war that the senior German officer had surrendered to him that day, not to Sergeant York. He even threatened Warner Brothers with legal action if it did not acknowledge his claims in the film.
At the release of the film, The Boston Globe ran an advertisement in the name of the seven men saying that they did not recall signing the affidavits corroborating Sergeant York's account and that none of them were "in agreement with Warner Bros.' or Sergeant York's version of what really happened 'over there.' "
The Germans, too, investigated the incident and found that Sergeant York could not possibly have carried out the feat alone. They suggested that the story was a compilation of several events that day. Almost all of those who have wrestled with the tale, like Mr. Birdwell, agree that the claim that he silenced 35 machine guns is pure fiction.
Still, the many inconsistencies do not detract from the fact that he and his comrades exhibited extraordinary courage that day.
Now competing groups obsessed with pinning down the truth — to the amusement of the local French — are using modern forensics to find the spot where Sergeant York stood.
A group of Tennessee college professors announced in March that they were "80 percent" certain that they had located the spot using metal detectors, hand-held global positioning devices and a sophisticated computer program that overlays historic and modern maps. But an American military intelligence officer working for NATO insists that the professors' location is wrong and that he is close to finding the correct spot.
"They're not even in the right valley," said the officer, Lt. Col. Douglas Mastriano, standing in a poplar grove with a metal detector that beeps and buzzes at buried shrapnel and cartridge casings.
Each side says its theories about where Sergeant York stood will be proved correct if it finds spent cartridges from a Colt .45 semiautomatic pistol that he and several witnesses said he fired at seven German soldiers who charged him with fixed bayonets.
But each .45 cartridge casing is less than an inch long, and the pan of a metal detector is only about a foot wide. The wooded area in which he could have been standing covers more than a square mile and is peppered with bits of exploded artillery and bullets, as well as spent rifle and machine gun cartridges.
In the end, it does not really matter who is right. The wooded valley where the fighting took place, its silence broken only by intermittent birdsong, still carries geography's sometimes powerful spell. Standing there, one can imagine the murmur of voices, followed by shouts, the sickening rattle of machine gun fire and, finally, the cries of falling men.
Mr. Birdwell and Colonel Mastriano have found American ammunition that may have come from York's bolt-action Lee-Enfield Model 17 rifle. Colonel Mastriano also found an American bullet buried in the dirt on the crest of the ridge that he says Sergeant York was firing at.
But his rifle has disappeared, and so there is no way of verifying whether he fired any of the rounds found. The proof, both sides say, will be finding cartridge casings from a Colt .45 semiautomatic like the one that Sergeant York fired — if they are to be found at all.