Hitler was very important to the growth of Nazi power from 1919 to the start of WWII. Firstly, in a year, he gained power in the German workers party, which in a decade would become the only party in Germany. Early on in 1919, his talent for public speaking and the use of the local army's resources drew large audiences to events sponsored by an organization that only had 100 to 200 members. An example of this is when he presented the party's official program to a gathering of February 24 1920,there was almost 2000 members. He was a great speaker, pulling in paying crowds to listen to his speeches. The party could not dismiss him, because he was pulling in the crowds and, at the end of 1920, the party had increased from a few hundred to a couple thousand. But there was internal opposition in the Workers party.
But as Hitler threatened to resign, the party committee agreed to give Hitler the title of 'Furher' in 1921. This was the first official use of the title associated with Hitler. Later on in 1926 he had gained complete control of the party without much opposition.
In 1923, Hitler tried a putsch, but failed because he didn't gain support of the army or the leaders in Bavaria. When Hitler went on trial for high treason, the judges were chosen by a nazi sympathiser, and so the trial was another propaganda platform for Hitler and the Nazis. He was eventually sentenced to five years in prison, with a parole period of nine months. In this time, he dictated his ideas in the 1st volume of "Mein Kampf", which would tell to the world about his future ambitions. This was a warning to those who would listen.
Now, after getting out...