Hereford, England—Two SAS instructors face court-martial over the death of three trainees.

The deaths occurred during the summer selection course in 2013.

On that day, Cpl James Dunsby, L. Cpl Craig Roberts, and Trooper Edward Maher died of heat exhaustion during a 16-mile march, in the Brecon Beacons, Wales.

It was the hottest day of the year.

The three Army reservists were trying out for the SAS reserve units, 21 and 23 SAS.

The SAS hold biannual selections, one in summer and another during the winter.

Due to the secrecy that veils Britain’s Special Operation Forces, the two SAS instructors have only been named as Captain 1A, the risk assessment officer of the course, and Warrant Officer 1B.

They face charges of negligence.  If found guilty, they could face up to two years behind bars and a dishonourable discharge from the Army.