Did they do it or not? That's the question that has dogged historians and climbing enthusiasts for decades.
Did George Mallory, 38, and Andrew 'Sandy' Irvine, 22, reach the summit of Mount Everest before they died, or did they die agonizingly close to becoming climbing gods?
Today, a quarter century after the discovery of Mallory's body, it was announced that a team sent by National Geographic magazine discovered what they believe to be Irvine's foot.
Still wrapped in a boot and sock bearing the 22-year-old's badge, he was found on Everest's central Rongbuk glacier, several hundred meters below where Mallory's remains were discovered.
It shed new light on mountaineering's greatest mystery. In the years since the June 1924 expedition ended in tragedy, experts have filled in many of the gaps about what happened to the pair on their final climb.
Sandy Irvine (left) disappeared aged 22 with her climbing partner, renowned mountaineer George Mallory, 38, in June 1924
The 1924 expedition was the second trip launched with the aim of achieving the first ascent of Everest.
Mallory and Irvine's fateful climb followed two unsuccessful attempts on the same expedition.
The first was made by Mallory and General Charles Bruce, who was initially the leader of the expedition until he fell ill.
The second attempt was made by Edward Norton – who took over as leader of the expedition – and the camp doctor, Dr. Howard Somervell.
For the third attempt, Mallory decided to take Irvine with her, despite his relative inexperience.
Irvine was a newcomer to the group, but the former engineering student had better knowledge of the group's heavy oxygen assemblies.
Irvine and Mallory reached Camp V – at 25,600 feet (7,600 m) – successfully and spent the night there on June 6.
Mallory left a note for the expedition's geologist that said: 'There is no wind here and things look promising.'
The next day, the pair moved into the small tent that expedition leader Edward F. Norton had established with Dr. Howard Somervell – the group's doctor at Camp VI (26,800 feet).
The partial remains of tragic Mount Everest climber Andrew 'Sandy' Irvine are believed to have been found – 100 years after he disappeared. What is believed to be Irvine's foot, encased in his sock and boot, was found in Everest's central Rongbuk Glacier, beneath the north face of the mountain. Irvine's remains were identified by the name stitched into his sock: AC Irvine
The paw and boot were found on Everest's central Rongbuk Glacier, below the north face of the mountain and at a lower altitude than where Mallory's remains were found in 1999.
A small team made up of Oscar-winning director and climber Jimmy Chin and fellow climbers and filmmakers Erich Roepke and Mark Fisher recently made the discovery, National Geographic revealed today. Above: Mr Chin with what are believed to be Irvine's remains
One of Irvine's feet was found hundreds of feet below where Mallory's body was discovered in 1999.
Andrew Irvine is photographed working on an oxygen bottle in the Everest Expedition camp in 1924
George Mallory is seen with Andrew Irvine at base camp in Nepal
Irvine (top left) and Mallory (top row, second from left) are pictured with the other members of the 1924 Everest expedition
Sandy Irvine seen when he was a student at Oxford University
Here, Mallory sent through the carriers two additional notes.
In one, Mallory told Odell that he and Irvine were “very sad to leave camp in such a situation.”
Mallory also complained about the “bloody load” of the two oxygen cylinders each of them would carry. He concluded by saying: 'Perfect weather for work!'
However, the climber, known for being forgetful and careless, forgot to take his hand-wound torch.
He also left behind magnesium flares that would have come in handy if the pair got into trouble.
Neither Mallory nor Irvine forgot their long-handled ice axes and strapped on their oxygen packs.
The sets were designed by the Air Ministry in London. Irvine modified them so the bottles were upside down, allowing the tube from valve to mouthpiece to be shorter – saving weight.
Mallory's other note said: 'Dear Noel, We will probably start early tomorrow (8) for good weather.
“It won't be too early to start taking care of ourselves, whether we're crossing the rock band under the pyramid or climbing the horizon at 8 p.m. Kind regards, G Mallory.
Irvine mistakenly said 'pm' instead of 'am'.
The next morning, the pair left their small tent after getting dressed for the next day.
They wore wool trousers, leggings (cashmere strips wrapped around the legs), studded boots and Burberry jackets.
The jackets were based on the ones Ernest Shackleton wore in Antarctica and were specially made.
Irvine insisted that his jacket have pockets sewn into the jacket. They boasted what were then innovative zippers.
Along with some 9mm white cotton rope, Mallory also had a Kodak camera that Somervell lent her.
In his pockets he had what British climber Graham Hoyland – Somervell's great-nephew – described in his 2013 book, Last Hours on Everest, as an “extraordinary collection of rubbish”.
He had nail scissors, a pencil, some 'tasty meat tablets', sunglasses and Vaseline. But he also forgot to take the compass.
A glove found in 2001 suggests that Mallory and Irvine used much the same route as modern climbers.
It could have fallen on the way up or on the way down.
The pair then left their next clue – an empty oxygen cylinder – 600 feet (180 m) before what is known as the First Step, the first of three rocky spurs.
Noel Odell wrote in his diary that he saw the pair – now two small black specks on the rock face – at around 12.50pm. He recalled: 'They were going strong to the top.'
However, what happened in the next few hours is uncertain.
What is known for sure is that a storm started around 2 pm.
Ice ax evidence suggests the pair descended the way they came.
Hoyland, who organized the 1999 expedition that found Mallory's remains, believes the older man slipped and fell.
He wrote: “Experienced climbers know that the descent is the most common time for this type of accident to occur; Exhaustion and hypothermia are setting in, concentration has been lost as a result of a false sense of security, and because of the incline you can't see the next step as clearly as you can on the way up.'
After Mallory fell, it is believed that Irvine dropped the ax to grab the rope, but was pulled down by the weight of his partner.
Mr. Hoyland adds: 'I think they fell together in the curious alternating fall which is often the fate of tied men: one falls, tearing off the other.'
It is known that Mallory survived the initial fall due to the fact that severe bruising formed on her waist.
He is then believed to have staggered towards Camp VI. His body was found about 270 meters away from the camp.
The Irvine ax was found in 1933. It was identified thanks to the distinctive notches carved into the wood. It was discovered on a small ledge below the First Step.
Nothing is known about Irvine's final minutes and seconds, or whether he survived the initial fall.
More details are unlikely to emerge unless the rest of his body is discovered.
A plaque commemorating George Mallory and Andrew Irvine placed on Mount Everest by Italian climbers. The inscription reads 'of the glory of the peaks forever in our hearts'
An artist's impression of George Mallory (top) and Andrew Irvine ascending the Second Step of Everest
Some experts believe that Irvine and Mallory may have actually achieved their goal before they died, because they were last seen approximately 250 meters from the summit and could have been descending when they fell.
The camera they carried was never found, but it may contain crucial evidence that they reached the summit.
Irvine's remains are now in the possession of the Tibet Mountaineering Association of China, the body that issues permits for climbing on the north side of Everest.
The discovery was reported to the Royal Geographical Society, the body that organized Mallory and Irvine's original expedition, together with the Alpine Club.
Irvine's family, which includes his great-niece and biographer, Julie Summers, has offered to compare DNA test results to the remains to confirm they belong to Irvine.
