April 4, 1963: College student Dorothy Bell, 19, waits for service that would never come at a downtown Birmingham lunch counter. She was arrested with 20 other sit-in demonstrators. | (AP Photo)

On August 28, 1963, Martin Luther King, Jr. stood on the steps of the Lincoln Memorial and delivered his famous "I Have a Dream" speech.

The Civil Rights movement leader spoke of peaceful protest, but also reminded Americans that enacting real change required taking a strong stand:

We have also come to this hallowed spot to remind America of the fierce urgency of now. This is no time to engage in the luxury of cooling off or to take the tranquilizing drug of gradualism. Now is the time to make real the promises of democracy. Now is the time to rise from the dark and desolate valley of segregation to the sunlit path of racial justice. [King, via American Rhetoric]

Many of those in attendance that day in Washington, D.C., had already met violent resistance. And many more would experience such moments before King's dreams became — in most cases — a reality.

Here, we look back at a struggle that was at times violent — and hope for a time in the future when such instances are once and for all truly a thing of the past.

May 4, 1963: A 17-year-old, defying an anti-parade ordinance in Birmingham, is attacked by a police dog. President Kennedy discussed the picture on May 4, after the image appeared on the front page of that day's New York Times. | (AP Photo/Bill Hudson)

May 8, 1963: A young woman is drenched by a fireman's hose as an anti-segregation march is broken up in Birmingham. | (AP Photo)

July 10, 1963: Police prepare to lift Mineral Bramletter in Brooklyn. The Congress of Racial Equality (CORE) was attempting to stop a cement truck from entering a hospital construction site. The protest stemmed from the lack of African Americans employed on the job. | (AP Photo/Robert L. Greger)

June 25, 1964: A group of white segregationists attack a group of blacks at St. Augustine Beach, Fla. | (AP Photo)

March 7, 1965: State troopers swing billy clubs while breaking up a civil rights voting march in Selma, Ala. | (AP Photo)

March 16, 1965: A college student calls for an ambulance to aid a fellow demonstrator, while an injured girl is carried away in the background. Mounted police broke up a march for voting rights in Montgomery. | (AP Photo/Perry Aycock)