Read further to learn about the real heroes behind this inspiration ... his concept of highly trained units. When the Second World War broke out, he was working as a cowboy in the United States.
The popular BBC series SAS Rogue Heroes has returned for its eagerly awaited second season, featuring Connor Swindells and Jack O'Connell reprising their roles.
SAS Rogue Heroes is based on the true story of how the SAS formed during the Second World War.