The Brecon Beacons is the chosen testing ground for one of the most revered fighting forces in the world - the Special Air Service.
A deceptive and gruelling environment, the deadly extent of its pitfalls was brought into sharp and shocking focus on Saturday 13 July, 2013.
"I've worked all over the world in 100-plus countries on every continent and actually, how many people have I known who have suffered with heat sickness? I can probably count the number on one hand." Rusty FirminEarly morning, three supremely fit, experienced soldiers set off on a 16-mile timed march.
It was a relatively short exercise in a series they had volunteered to undertake in a quest to being accepted into "The Regiment".
None of them made it back.
A month-long inquest into why these soldiers collapsed delivered a conclusion of neglect.
Here BBC Wales news website takes a closer look at one of Wales' last true wildernesses, its significant role in the history of the SAS and why it is no stranger to tragedy.
Following a report into the deaths of the recruits, the SAS will soften its selection process.