Deepak Shukla

    21 SAS (Reserves) — applying, selection and preparing for it

    I applied to 21 SAS as a reservist and wrote down what actually happened at each stage, rather than what the forums say happens. Start here for what the unit is and how the process runs, then read the diary posts and the training underneath.

    What 21 SAS is

    21 SAS is one of the reserve units of the UK Special Forces. Reservists hold civilian jobs and train alongside them, which is the part people underestimate: the fitness, the navigation and the hours on the hill all have to be built around a working week, on your own, for months, before anyone assesses you. For the official position on the unit, its role and current entry criteria, the Army publishes its own pages — treat those as the authority and this site as what it felt like from the inside.

    How the process runs

    It begins as paperwork and a conversation, not a hillside. There is an application, contact with the unit, and briefing and assessment weekends before anything resembling selection proper. My write-ups cover the application itself and the ATC Pirbright weekend in order, including what the staff appeared to be looking for and where people around me came unstuck.

    What actually binned people

    Rarely raw fitness. It was feet, kit, food and pacing — blisters from new boots, a bergen loaded heavy too early, nothing eaten, going off too fast on the first climb. Almost every one of those is decided in the months before, not on the day.

    How I'd prepare

    Aerobic base first, for weeks, before any load. Hills before weight. Weight added slowly and late. Back-to-back weekend days in the exact kit you'll use, navigating for yourself. Then back off before the event. The free prep guide below sets that out as a twelve-week shape, and the endurance archive on this site is the long version of how I built it.

    The questions people ask

    Get my 21 SAS reserve selection prep guide

    What the stages are, what I was training to before I applied, and how I'd build the twelve weeks before a selection weekend. Written from my own application, free, no pitch.

    Everything I've written on this

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