Special Forces unit: British SAS, World War Two The Special Air Service was formed by David Stirling in 1941. Its purpose was to act as a desert raiding airborne force unit that would secretly fight behind enemy lines in the North African Campaign. The first unit of the SAS, of around 60 men was called the "L" Detachment, Special Air Service Brigade. This name was used to confuse the Axis into thinking it was a much larger paratrooper regiment.