The Special Air Service is the longest active special missions unit in existence and has remained one of the best. Staffed with the toughest and most resourceful enlisted and commissioned soldiers the United Kingdom has to offer, the SAS only accepts the cream of the crop. Of all candidates who try to earn the coveted beige beret and the title of “Blade,” only the very best make it through.

In order to thin out the herd, the SAS holds one of the most arduous and rigorous selection and training programs in the modern special operations community. Timed cross-country marches, treks through jungles, and a mountain climb are just a few of the challenges that make joining the SAS an extreme task.

Typically, the SAS runs two selection periods every year, one in summer and the other in winter. While any fully-trained member of the British Armed Forces may apply for selection, the bulk of candidates tend to come from light infantry, airborne, and commando units.

Selection lasts around five months and consists of multiple phases, each designed to break down every candidate and push them to their limits and beyond. That’s probably why the program has an astonishing 90 percent fail rate. Many drop out due to stress or injury — those who remain must meet and exceed the high standards set by the selection cadre.