Formed by David Sterling to aid montgomery
in North Africa in WWII, the SAS was a team of five officers and sixty men who were all drawn from the commando units. They were put through gruelling training. Early failures were overlooked in the light of successful tactics and destructive capability shown later in the war.
When one member was captured, he escaped, and walked 200 miles in eight days of blistering desert heat with no more than a map, compass and a pair of shorts to rejoin his comrades.