BILL MOYERS: Many many years ago, I was a young White House Assistant, when President Johnson at first wanted Martin Luther King to call off the marching, demonstrations, and protests. The civil rights movement had met massive resistance in the south, and the south, because of the seniority system, controlled congress, making it virtually impossible for congress to enact laws giving full citizenship to black Americans, no matter how desperate their lives. LBJ worried that the mounting demonstrations were hardening white resistance.

He had been the master of the Senate, the great persuader, who could twist your arm with such flair and flattery you thought he was actually doing you a favor by wrenching it from its socket. He reckoned that with a little time he could twist enough arms in Congress to end, or neutralize, the power of die-hard racists—all of them, including some of his old mentors, white supremacists who threatened to bring the government, if not the country, to its knees before they would see blacks eat at the same restaurants, go to the same schools, drink from the same fountains, and live in the same neighborhoods as whites.

As the pressure intensified on each side, Johnson wanted King to wait a little longer and give him a chance to bring Congress around by hook or crook. But Martin Luther King said his people had already waited too long. He talked about the murders and lynchings, the churches set on fire, children brutalized, the law defied, men and women humiliated, their lives exhausted, their hearts broken. LBJ listened, as intently as I ever saw him listen. He listened, and then he put his hand on Martin Luther King's shoulder, and said, in effect: "OK. You go out there Dr. King and keep doing what you're doing, and make it possible for me to do the right thing." Lyndon Johnson was no racist but he had not been a civil rights hero, either. Now, as president, he came down on the side of civil disobedience, believing it might quicken America's conscience until the cry for justice became irresistible, enabling him to turn Congress. So King marched and Johnson maneuvered and Congress folded.

NEWS COVERAGE: President Johnson calls for all Americans to back what he calls a turning point in history.

BILL MOYERS: The Civil Rights Act of 1964 ended segregation in public places.

MARCHERS: We shall overcome...

BILL MOYERS: But they weren't done. King kept on marching, this time for the right to vote, and once again Johnson kept his word, and did the right thing. As one of his young assistants, I stood on the floor of the House that ides of March when morality and politics converged, and watched the faces of congress transfixed, mesmerized, knowing they were riding the surf of history as the president of the United States enlisted all of us in the cause.

LYNDON JOHNSON: It's all of us, who must overcome the crippling legacy of bigotry and injustice. And we shall overcome.

BILL MOYERS: As he finished, Congress stood and thunderous applause shook the chamber. Johnson would soon sign into law the Voting Rights Act of 1965 and black people were no longer second class citizens. Martin Luther King had marched and preached and witnessed for this day. Countless ordinary people had put their bodies on the line for it, been berated, bullied and beaten, only to rise, organize and struggle on, against the dogs and guns, the bias and burning crosses. Take nothing from them; their courage is their legacy. But take nothing from the president who once had seen the light but dimly, as through a dark glass—and now did the right thing. Lyndon Johnson threw the full weight of his office on the side of justice. Of course the movement had come first, watered by the blood of so many, championed bravely now by the preacher turned prophet who would himself soon be martyred. But there is no inevitability to history, someone has to seize and turn it. With these words at the right moment—"we shall overcome"—Lyndon Johnson transcended race and color, and history, too—reminding us that a president matters, and so do we.