David Seath, a Royal Artillery captain from Plymouth collapsed after suffering a heart attack three miles from the finish line while taking part in the London Marathon. He was rushed to hospital where he died. Heartbroken pals are now planning to walk the final three miles and complete his run in his memory.
A fundraising page has also been set up in his memory by fellow Army officer and close friend James Walker-McClimens, 34.
Seath had two Masters degrees from the University of Aberdeen before competing his Army training at Sandhurst in 2010.
Based in Plymouth, Devon, he had served in Afghanistan, in the Nahri Saraj district of Helmand province.
He had done other charity work and worked with groups which helped visually impaired Army veterans, including Royal Blind and Scottish War Blinded.
The previous death in the London Marathon was in the 2012 event when Claire Squires, 30, from North Kilworth, Leicestershire, died.
A fund-raising page set up in her memory raised almost £1million for the Samaritans.