“The SAS and (presumably) the SEALS are units you apply to join having already served some time in a regular branch.”
Nope. No “regular” time required. In fact, many units throughout the DoD prefer that you never step foot into another unit only to learn bad habits they then have to unlearn.
Well, I’ll defer to people who know better on that score. It does seem a bit strange that they would recruit from such a massive pool of untested civilians who they know very little about before they even start the selection process, but maybe they have their reasons.
From what I understand of the SAS, you already have to be a member of HM armed forces before you attempt to join them.
Also from what I understand, the Parachute Regiment and the Royal Marines are the most common units that the SAS recruit from. They will already have gone through an intense selection process and level of training at Catterick or Lympstone respectively, so the pool the SAS is drawn from will already be full of highly-trained, competent and extremely tough men before they even start whittling it down to the very few individuals that will survive this even tougher selection process and in order to get ‘badged’...