The SA was formed in August 1921, NSDAP's private army.
Hitler hired the unemployed, students and ex-soldiers into the SA, as they were infuriated with the WG
Hitler used the SA to:
Control crowds at meetings
Start fights on the streets
Disrupt the meetings of opposition groups like the KPD
Strengthen the image of the NSDAP
The SA became problematic
By 1922, there were 800 Brownshirts, and it was increasing
Röhm became leader in 1923 and was popular and Hitler didn't have direct control
To combat this, Hitler hired personal bodyguards from the SA.