NSDAP

(The NSDAP's official logo.)

The NSDAP was founded in 1919 by Anton Drexler, Gottfried Feder, Dietrich Eckart and Karl Harrer. It was originally named DAP, Deutsche Arbeiterpartei (German Workers' Party). The party became one of many völkisch movements that existed in Germany at the time, which believed that the sole cause of defeat was the collapse of the home front, the Dolchstosslegende ("stab in the back"), and advocated the belief that Germany should become a unified "national community" (Volksgemeinschaft) rather than a society divided along class and party lines. The DAP was violently opposed to the Social Democratic Party (SPD) and particularly to the newly-formed Communist Party of Germany (KPD).
In the same year, the political party attracted the attention of the German authorities, who were suspicious of any organization that appeared to have subversive tendencies. A young corporal, Adolf Hitler, was sent by German army intelligence to investigate the DAP. While attending a party meeting, Hitler got involved in a heated political argument and made an impression on the other party members with his oratory skills. He was invited to join, and, after some deliberation, chose to accept. Among the party’s earlier members were Rudolf Hess, Hans Frank and Alfred Rosenberg, all later prominent in the Nazi regime.
Hitler became the 55th member of the DAP. Over the following months, the DAP continued to attract new members, while remaining too small to have any real significance in German politics. On 24 February 1920, Rudolf Jung persuaded Hitler to follow the NSDAP naming, the party added "National Socialist" to its official name, becoming the National Socialist German Workers' Party.
Hitler became party chairman on 28 July 1921, Hitler soon acquired the title "Führer" (leader), and so Hitler came to be the sole leader of the party and he alone decided its policies and strategy.