Answer:
The boycott and protest was led by Martin Luther King Jr and this was because of the discrimination of a black lady called Rosa Parks in a bus in Montgomery.She was arrested for not giving up her seat for a white person to use. The blacks decided to boycott the usage of the buses for several months. The boycott was later called off when the Supreme Court pointed out that the segregation was unconstitutional.
Yes, the citizens of Montgomery as well as those of the US Supreme Court was necessary for its success.