<span>When an activist decides to use a song, speech, or video to communicate his message, he is using strategic support to reach his audience. An activist is someone who passionately believes in a cause.</span>
Segregation was described as wilderness as a way of indicating the inhumaneness of this treatment, for literally wilderness indicates a place without civilization or society.
Injustice is not always a wilderness, although it sometimes can be. Injustice acts within established society all the time -- sometimes, de jury, it can be under the guise of a law-abiding action, but in reality (de facto) it could be injustice. For example, Donald's Trump urge to deport and restrict immigrants from certain countries reflects injustice in an established environment (in my opinion, of course).
The example of anecdote is:
As a young child, I remember loving the taste of popcorn when I went to the movie theater.
The anecdote is the oral stories which are of importance to the subject at hand. They add personal knowledge and experience to the subject. The above sentence tells about the story of popcorn that the speaker had. The story is a personal experience of the speaker. While the other sentences also contain some information about popcorn but they are facts and not personal experiences.