Gerald Ford said in his taking over the presidency from Nixon, 'Our long national nightmare is over;' rather the reverse happened when James Earl Ray killed Martin Luther King, Jr. As David Brooks said this week*:

The idea was to reduce ugliness in the world by reducing ugliness in yourself. King argued that “unearned suffering is redemptive.” It would uplift people involved in this kind of action. It would impose self-restraint. The strategy of renunciation and the absorbing of suffering was meant to guard against all that. In short, the method relied upon a very sophisticated set of paradoxes. It relied on leaders who had done a lot of deep theological and theoretical work before they took up the cause of public action. Nonviolent protest, King summarized, “rests upon two pillars. One, resistance, continuous military resistance. Second, it projects good will against ill will. In this way nonviolent resistance is a force against apathy in our own ranks.

With the death of King, the things his theological undertaking was meant to guard against developed. Again in David Brooks words:

The leaders understood that even people in the middle of just causes can be corrupted. They can become self-righteous, knowing their cause is right. They can become smug as they move forward, cruel as they organize into groups, simplistic as they rely on propaganda to mobilize the masses.

King's dream was no longer; a nightmare began. *http://www.nytimes.com/2013/08/27/opinion/brooks-the-ideas-behind-the-march.html?ref=davidbrooks&_r=0