What is the primary purpose of propaganda?
to inform the reader about possible options
to confuse the reader
to acquire additional information about the reader
to get the reader to adopt a particular point of view

The primary purpose of all propaganda is to convince the public or part of the public to accept the message of the propaganda distributor without question. This message might support a war, claim that one race is superior or insist that a political opponent is evil or unqualified. 
Hope i helped!
-Sammy