Although based at Achnacarry nearly all the big houses in Lochaber were overtaken by them. Because of all this military training the Government banned people from visiting much of Lochaber. In fact nobody could cross the Caledonian Canal unless they lived beyond it, or had a special pass.

After arrival at the Centre, the trainees were taught tactics, war techniques, and devised many new ones. The trainees used the latest weapons and equipment and trained to be experts in handling captured weapons. They were also taught unarmed combat and survival skills in the unpredictable mountain climate of Lochaber. They trained in physical fitness, survival, orienteering, close quarter combat, silent killing, signalling, amphibious and cliff assault, vehicle operation, weapons (including enemy) and demolition.

Night training was greatly emphasised, darkness was an ally the Commandos were trained to exploit this. Live ammunition, always used at the Centre, to provide battle conditions involved risks and sadly a number of trainees were killed during training.