Advent of the Fuehrer By summer of 1921, Hitler had assumed undisputed leadership of NSDAP By summer of 1921, Hitler had assumed undisputed leadership of NSDAP Provided first glimpse at ruthlessness & shrewdness with which he was to gain success Provided first glimpse at ruthlessness & shrewdness with which he was to gain success While in Berlin, other members of Nazi Party attempted to weaken Hitler’s power While in Berlin, other members of Nazi Party attempted to weaken Hitler’s power