Martin Luther King Jr.’s assassination, on April 4, 1968, marked the end of an “extraordinary moment of progressive reform,” writes op-ed columnist E.J. Dionne Jr. “In The Liberal Hour, an important new history of the ’60s that will be published in July, Colby College scholars G. Calvin Mackenzie and Robert S. Weisbrot note that for all its deficiencies, the period of liberal sway ‘demonstrated what democratic politics can produce when public consensus crescendos, when coherent majorities prevail, and when skilled leaders provide direction, inspiration, and relentless energy.'”