Three soldiers died from overheating during a training exercise on the Brecon Beacons in Powys, a pre-inquest hearing has been told.
L/Cpl Craig Roberts, 24, of Penrhyn Bay, Conwy, and L/Cpl Edward Maher, 31, died from hyperthermia on 13 July last year.
Cpl James Dunsby, of the Royal Yeomanry, based in Swindon, died in the Queen Elizabeth Hospital, in Birmingham, on July 30.
Cpl Dunsby lived in Trowbridge with his wife Bryher, his funeral taking place at the town’s St James’ Church in August last year with police closing off nearby streets.
The hearing in Solihull, West Midlands, was told the soldiers suffered hyperthermia, which occurs when the body's temperature rises substantially above what is considered normal.
Cpl Dunsby's death was also as a result of multi-organ failure following the 40-mile (64km) hike when temperatures reached 29.5C (85F), said coroner Louise Hunt
The soldiers were among six men rescued from the Brecon Beacons during the exercise, which had been part of a four-week trial for the Territorial Army's SAS reservists.
In November the Health and Safety Executive ordered the Ministry of Defence to take action to deal with risks on exercises following the men's deaths.
The MoD said at the time it was implementing all the recommendations in the notice.
Another pre-inquest hearing looking into the men's deaths will take place in August.
A decision on whether to pursue manslaughter prosecutions as a result of their deaths is expected this month.