The exhausted climber scanned the frozen slope above him as darkness began to engulf the mountain. "Lino! Achille! Where are you?" he cried. The only answer was silence. It was July 30, 1954. At the end of a marathon day of load-hauling, Walter Bonatti and his gritty companion, the Hunza porter Amir Mahdi, had reached an altitude of 26,575 feet (8,105 meters) on Pakistan's K2, the world's second highest mountain.

At that moment, the K2 summit—arguably the greatest mountaineering prize of the day—lay tantalizingly close to the grasp of a large Italian team. Just four years before, with the French first ascent of Nepal's Annapurna in 1950, what would come to be called the golden age of Himalayan mountaineering had been launched. By the mid 1960s, all 14 of the world's peaks that surpass the benchmark altitude of 8,000 meters (26,240 feet) would be climbed for the first time.

On that July morning, the Italian team's climbing leader, 40-year-old Achille Compagnoni, and his partner, 29-year-old Lino Lacedelli, had ascended the mountain to establish Camp IX, an advance post for the final K2 summit push. Though Walter Bonatti, at 24, was the youngest member of the expedition, he had already forged a sterling climbing reputation by pioneering some of the most daring routes in the Alps. He was the strongest member of the Italian team. But he had not been chosen to make the first summit attempt.

Instead, accepting his role in support of the summit pair, Bonatti had set out that morning with Mahdi, the most experienced and respected Hunza climber of his day, on the dangerous quest to carry crucial oxygen cylinders up to Compagnoni and Lacedelli. Near the end of the day, the two men had at last reached the high, safe shoulder of snow at 25,900 feet (7,900 meters) where the whole team had agreed to place Camp IX the night before. The Camp IX tent, however, was not where it was supposed to be. Driving farther upward toward nightfall, Bonatti had now committed himself and Mahdi to sharing the inadequate tent with Compagnoni and Lacedelli. With the oxygen, however, the two men carried the only hope that their comrades could get to the summit on July 31. As night fell, Bonatti cried out to his teammates.

"Achille! Lino!" he shouted again and again. "Why don't you answer?" It was now almost pitch dark. Mahdi had no headlamp, and Bonatti's had ceased to work.

Abruptly, a light pierced the gloom. One of the climbers must have heard Bonatti's cries. The light came from a camp that lay several hundred feet to the left of the main route to the summit and that was camouflaged by protruding rocks. Bonatti heard Lacedelli call out, "Have you got the oxygen?"

"Yes!"

"Good! Leave it there and go straight down!"

What could Lacedelli mean? "I can't!" Bonatti yelled back. "Mahdi can't make it!"

As abruptly as it had flashed on, the beam of light went off.

In absolute darkness, Mahdi screamed ("like a madman," as Bonatti later wrote), "No good, Compagnoni Sahib! No good, Lacedelli Sahib!"

"Lino! Achille! Help us, damn you!" Bonatti wailed. Not a word came from Camp IX.

In a fog of rage and despair, Bonatti turned to the slope before him and hacked out a ledge with his ice ax. Never before had anyone attempted, let alone survived, an open bivouac at such an altitude.

It was just a year before the Italian K2 campaign, in 1953, that Everest had been ascended, by Edmund Hillary and Tenzing Norgay, as had Pakistan's Nanga Parbat, the ninth-highest mountain, by the Austrian Hermann Buhl. Still, 11 of the 8,000-ers remained inviolate. K2 would ultimately prove the most difficult of the world's 14 highest peaks, as well as arguably the most dangerous. Its unique challenge: the extreme steepness of every one of its ridges and faces, the fact that some of its hardest climbing lies very high on its flanks—and a fiendish scarcity of good campsites.

With the bitter echoes of World War II still reverberating, the great expeditions of the golden age took on an intensely nationalistic cast. All the principal players in the war would now meet in a new theater, the Himalaya—even the Japanese, who made the first ascent of Nepal's 26,781-foot Manaslu in 1956. For the French, who had never before distinguished themselves in the Himalaya, the revolutionary 1950 ascent of Annapurna served as a heroic epic that validated the whole country, still smarting from the shame of its occupation by the Germans.

It was not an accident that the leaders of the Himalayan expeditions of the 1950s tended to be autocrats with military dispositions and backgrounds: Sir John Hunt on Everest, chosen over the blithe vagabond Eric Shipton, who was bumped from the job at the last minute; on Annapurna, Maurice Herzog, who exacted from his teammates formal pledges of unquestioning obedience; and the German martinet Karl Maria Herrligkoffer, who sued Hermann Buhl for violating orders rather than congratulating the climber after he summited Nanga Parbat.

For the Italians, defeated in the war, their duce shot by the conquerors and hung by his heels in a public square, the potential glory of K2 demanded just such a leader: 57-year-old Professor Ardito Desio. And there was no question which team member was likeliest to set the first foot on the summit: Achille Compagnoni was Desio's prot�g�. Other members of the party reported that they were treated by Desio with something near contempt. As Lino Lacedelli would tell me in 2003, "We called him 'Il Capetto' [the Little Chief]. From base camp, he typed up daily orders. Order 13: 'Who will not obey my orders will be punished with the heaviest weapon in the world—the press.' "

Throughout 2004, Italy has basked in a prolonged celebration of the 50th anniversary of K2. Newspaper retrospectives, TV documentaries, a newly issued postage stamp, and a much-hyped commemorative expedition to the mountain have revived the original glory of the first summit. Compagnoni, now 90, and Lacedelli, now 79, who reached the top of K2 at 6 p.m. on July 31, 1954, rest securely in their country's pantheon of adventurers.

Walter Bonatti went on, during the 11 years after K2, to round out a roster of astounding first ascents that enshrine him today, at age 74, as one of the living legends of mountaineering. No less an authority than Himalaya veteran Doug Scott, in his book Big Wall Climbing, calls Bonatti "perhaps the finest alpinist there has ever been."

Yet Bonatti declined to take part in this year's 50th anniversary festivities. For him, K2 was not a glorious triumph.

Ever since the first ascent of the Matterhorn in 1865—a feat forever marred by the deaths of four climbers on the descent—many of mountaineering's finest achievements have been tarnished by bitter fallings-out among teammates, and even by claims that great alpinists, in extremis, have performed morally indefensible deeds. Such imbroglios seem to be an inevitable by-product of enterprises in which national pride, personal fame, and sheer egomania play so large a part.

Last December, to interview Bonatti, I traveled with French journalist Charlie Buffet to Dubino, an ancient hamlet on the Adda River, just east of the northern end of Lake Como. Appropriately, Bonatti's house is the highest in the village, and now, on the day before the solstice, facing south across the shadowed valley, it soaked every possible erg of radiant warmth from the sun as it made its low traverse above the opposite hills.

Bonatti's reputation in the climbing world conjures up an uncompromising idealist, a loner who always sought his own path, an angry victim of the attacks of his jealous, less gifted rivals. From the first moment, however, Bonatti seemed to me gracious and approachable, happily grabbing our suitcases and jogging with them to our guest rooms. He stands only about five feet seven inches tall, but, even in his eighth decade, his body exudes power. Right away I noticed the man's thick, strong fingers, which he wields constantly as he talks, tracing shapes in the air or slapping his palms on the table for emphasis. He has a full head of fine silver hair, a big, blunt nose, and—surprisingly in a man whose life has been beset by rivalry and controversy—the genial wrinkles of someone who laughs a lot.

Speaking Italian that Charlie translated for me, Bonatti recalled the forced bivouac of July 30, 1954. "I could have gone down in the dark by myself, even without a headlamp," he said. "But Mahdi was out of his mind. Several times I had to keep him from running away.

"It took a long time to dig a ledge out of the icy slope. We sat very close together. Mahdi was too tired to take his crampons off, so I did it for him. Otherwise his frostbite would have been even worse.

"I spent the whole night looking at my five fingers to see if they were still there. Making up problems in my head to see if I could still think right. I kept banging my legs with my ice ax—that was before we knew it was a bad thing to do." (Pounding a frozen extremity can break blood vessels, exacerbating frostbite.) "It was as if one breath lasted the whole night."

In the wee hours, a sudden snow squall descended on the mountain, smothering the climbers in blowing snow. Three times the two climbers had to dig themselves out.

As soon as first light arrived, Mahdi took off, almost running down the mountain toward Camp VIII. "In the morning," Bonatti remembered, "I was a piece of ice. I didn't have the strength to restrain him. All I could do was put on his crampons. My heart was beating fast as I watched him go. Then he reached a flat area, and I knew he was OK."

In the official account of the expedition, La Conquista del K2 (Victory Over K2), published the year after the ascent, team leader Ardito Desio tells a very different story from the one we were now hearing from Bonatti. Paraphrasing Compagnoni and Lacedelli, Desio writes that the lead pair never dreamed that Bonatti and Mahdi had bivouacked rather than descending. In the morning, when they saw Mahdi hurrying down the slope, "We were simply flabbergasted. . . . We thought of all the possible explanations except the right one. How could we suspect the truth—namely that two men had survived the rigors of a whole night spent in the open at an altitude of more than 26,000?"

Pick up the September issue of Adventure to read the full article, which sheds new light on this controversial first ascent 50 years later.

From the print edition, September 2004

Where to Live and Play Now: Spend a week in these enticing base-camp burgs and you may never go home.

Pelton's World: Surviving a foreign fleecing

The River Wilder: Maine's classic American river trip

K2 at 50: The controversy surrounding the world's most vicious mountain