From The Writer's Almanac:
It's the anniversary of the first March from Selma to Montgomery, Alabama (1965), known as "Bloody Sunday." Six hundred civil rights activists left Selma to march the 54 miles to the state capitol, demonstrating for African-American voting rights. They got six blocks before state and local lawmen attacked them with billy clubs and tear gas.
ABC News interrupted a Nazi war crimes documentary to show footage of the violence. In the blink of a television set, national public opinion about civil rights shifted. Demonstrations broke out across the country.
Two weeks later, the March from Selma made it to Montgomery, led by Dr. Martin Luther King, federal court protection, and these words from President Lyndon Johnson: "There is no issue of States rights or national rights. There is only the struggle for human rights." When they got to Montgomery, they were 25,000 strong.