Britain's Prince Harry and a team of injured troops from the United States, Canada and Australia are set to reach the South Pole on Friday after a 320-kilometre trek.
The expedition was initially conceived as a race but it was abandoned due to concerns about the safety of the participants, some of whom lost limbs fighting in Afghanistan and Iraq.
The teams decided to continue their trek, however, dragging 70-kilogram sleds through the bitter cold and high winds to the globe's most southerly point.
Harry, 29, who serves as an army helicopter pilot, joked that the expedition now looked set to be completed on Friday 13th, which was "unlucky for some, lucky for us".
"The wind has dropped down, which is nice. I think everyone is feeling a bit tired but slowly getting into the rhythm," the fourth-in-line to the throne said in a message released earlier this week.
"Only just got into the rhythm now and it has almost finished."
The veterans are enduring temperatures as low as minus 35 degrees Celsius and wind speeds of around 80 kilometres per hour.
Walking With The Wounded raises funds to retrain injured troops and help them find new careers outside the military.
Harry joined the charity for part of a trek to the North Pole in 2011, but had to come home early to be best man at his brother Prince William's wedding.
