The Early History of String Theory and Supersymmetry
  This lecture presents a brief overview of the early history of string theory and supersymmetry. It describes how the S-matrix theory program for understanding the strong nuclear force evolved into superstring theory, which is a promising framework for constructing a unified quantum theory of all forces including gravity. The period covered begins with S-matrix theory in the mid 1960s and ends with the widespread acceptance of superstring theory in the mid 1980s. Further details and additional references can be found in Schwarz (2007). 
John H. Schwarz
physics.hist-ph hep-th