Explorer Henry Worsley has died after suffering exhaustion and dehydration during an attempt to cross Antarctica.
The ex-Army officer, 55, was 30 miles short of his goal of becoming the first person to cross the continent unaided.
In a statement, his wife Joanna said she felt “heartbroken sadness”. Mr Worsley, from Fulham in London, died of “complete organ failure”, she added.
The Duke of Cambridge said he was “very sad” to hear of Mr Worsley’s death, while David Beckham also paid tribute.
“He was a man who showed great courage and determination and we are incredibly proud to be associated with him,” Prince William said.
In a message published before he was airlifted to Chile for treatment, Mr Worsley wrote: “The 71 days alone on the Antarctic with over 900 statute miles covered and a gradual grinding down of my physical endurance finally took its toll today, and it is with sadness that I report it is journey’s end – so close to my goal.”
The ReMark Group, which was supporting Mr Worsley’s effort, said in a statement: “When Henry was picked up by Antarctic Logistics and Expeditions (ALE), he was suffering from exhaustion and dehydration.
“He was flown to a hospital in Punta Arenas [in Chile] where he was found to have bacterial peritonitis.
“This resulted in Henry undergoing surgery but in spite of all the efforts of ALE and medical staff, he succumbed.”
Peritonitis is inflammation of the peritoneum, the thin layer of tissue that lines the inside of the abdomen. According to the NHS, most cases come from injury or infection in another part of the body.
On Instagram, David Beckham said he was “lucky to have met Henry”, who had “served our country for so many years”.
And adventurer Bear Grylls tweeted: “We are devastated by this loss. One of the strongest men & bravest soldiers I know. Praying for his special family.”
Mr Worsley began the 1,100-mile (1,770km) coast-to-coast trek in November, pulling a sledge containing his food, tent and equipment.
The plan was to cross the continent “unassisted and unsupported” – with no supply drops or help from dogs or any other source.
He had passed his target of raising £100,000 for the Endeavour Fund, which helps injured and sick servicemen and women.
In a statement, the fund said it was “devastated” by news of Mr Worsley’s death.
‘Drive’ for soldiers
In October, he told the BBC he expected to lose two stone (12.7kg) during the challenge.
He said his journey should take 75 days and he would take enough food for 80 days, adding: “I could make it last a bit longer.”
Asked if he was “mad” to take on the challenge, he said: “There is no black art to sliding one ski in front of the other.
“What will drive me on is raising money for these wounded soldiers.”