Throughout history there has always been a need, in military forces, for special units. In the past, these units have usually been ad hoc formations that were disbanded after their mission was complete. It has only been since the early 1950s that such units have remained active, but even in recent times special purpose, special mission units have been organised and used for a period of time or for a specific mission and then either deactivated or replaced by other units.

This unique approach to the history of American special forces examines their development through a number of operations, ranging from the French and Indian War in the 18th century through to the Vietnam War. From the Son Tay raid to the Force at la Difensa and Rogers' Rangers, the operations are diverse in both organisation and purpose, but all contributed to the overall mission of their theater or larger organisation, thus proving the continuing need for special units throughout history and even today.