Highly-trained and immensely skilled, the SAS are widely regarded as one of the best Special Forces units in the world. Their missions are uniquely diverse: counter-terrorist responses at home and abroad; deep penetration for reconnaissance and guiding air strikes; training and supporting indigenous forces; counter-insurgency in collaboration with U.S. Delta Force, SEAL Team Six, and other foreign Special Forces; mobile operations in support of conventional forces; targeting terrorist leaders and manhunting war criminals, to "direct action" raids.

This book charts the changing...