Catford Army Reservists from the explosive ordinance disposal squadron will next month attempt the six peaks challenge in just two days in memory of a colleague shot in Afghanistan.
The team of 14, including eight climbers and six support staff, will climb all six mountains on August 9 totalling almost 6,600m in just 48 hours in memory of Will Blanchard.
Sapper Blanchard was killed by a gunshot wound in October 2010 while dealing with a suspect explosive device in the Nahr-e-Saraj region of Southern Afghanistan.
In April 2013 a road was named after him at a ceremony attended by his widow Suzanne and the Mayor of Gosport in his home town in Portsmouth.
This year's Blanchard challenge, which raises money for charities, will require tremendous determination from the fleet with time and endurance being the main obstacles in achieving their goal.
Captain Tom Roach, team leader, said: "It's very humbling to be part of a team that has volunteered year after year in memory of our Brother in Arms, Will Blanchard. The support we receive is simply overwhelming."
The team will start in Scotland where they will first climb its highest mountain, Ben Nevis (1344m) and then Ben Macdui (1309m). They will then make their way to the Lake District via minibus to climb England's highest mountain, Scafell Pike (978m) and Scafell (964m). Their final stop will be in Snowdia in Wales where they will climb Mount Snowdon (1085m) and finishing with Cadair Idris (893m).
Since its creation four years ago the Blanchard Challenge has raised approximately £3,000 each year for various charities including Help the Heroes, Veterans Aid, Heart of Kent Hospice and Wisdom Cancer Care.
The challenge has also seen the team walk Hadrian's Wall, canoe across Lake Windermere and cycle 180 miles in two days.