A post-mortem is due to be held on Friday of a soldier who died whilst training in Brecon.
26-year-old Joshua Hoole, from Scotland, was taking part in a training exercise for the Platoon Sergeants' Battle Course - a course taken by infantry soldiers who want to progress to the rank of sergeant.
It's been described as "both mentally and physically demanding".
Mr Hoole was a member of The Rifles Regiment. One of his commanding officers said the regiment was 'devastated'.
Mr Hoole died on the training exercise on what was the hottest day of the year in the Brecon area of Wales, where temperatures peaked at just above 30C.
It comes just three months after the Defence Select Committee published a report calling for the Ministry of Defence (MoD) to be liable for prosecution for the deaths of armed forces personnel.
Defence Minister Harriet Baldwin confirmed that the MoD will carry out a full investigation into his death.