The leader of this march was Martin Luther King jr a baptist preacher and the leader of the civil rights movement. He believed in a very effective tactic that he got from gandhi. This very effective tactic in a peaceful movements such as sit ins, protests, and marches.
A big obstacle for this bloody sunday is George wallace alabama governor. He was furious about this march and ordered forces to stop them. He filled up the jails with African American protesters. The protesters got hosed down, beat, a few even got killed. until the president ordered them to stop.
This made a big effect especially down south. When America saw people peacefully marching while getting hosed down and beat this inspired everyone to give blacks the right to vote and give them the freedom they deserve. Because every person is equal and should be treated the same.
This is similar to "black lives matter" movement when they blocked I35-W bridge in minnesota. they are similar because they both are peaceful movements.