Diametrically different as he was from Randolph in every ideological way, Governor Wright matched him in brinkmanship. Less than two weeks after Truman had delivered his 1948 State of the Union speech, with its appeal for civil rights, the governor declared in his inaugural address that the program, if enacted, would “wreck the South and our institutions“ and “eventually destroy this nation and all of the freedoms which we have long cherished and maintained.”

Several weeks later, Wright convened 4,000 true believers waving Confederate flags and whooping out rebel yells to begin organizing the States’ Rights Democratic Party. By the time the Philadelphia convention began, he was maneuvering on two parallel tracks. As the head of Mississippi’s delegation, he could organize opposition to both Truman’s nomination and a genuine civil-rights plank from within the Democratic Party. Meanwhile, if he lost those battles, he had already arranged for special railroad cars to transport the indignant Southerners straight to Birmingham, Ala., to convene their own breakaway Dixiecrat party.

Into the maelstrom came Humphrey, filled with idealism and trepidation. He had been warned by the party’s chairman, J. Howard McGrath, that pushing a civil-rights plank would “be the end of you.” Humphrey’s proposal — with its call for equal rights for racial and religious minorities in voting, employment, and military service — then lost in a vote by the platform-drafting committee. Only some adroit parliamentary maneuvering gave him a second, final chance to sell the plank in a speech to the full convention. It took place early in the afternoon of July 14, 1948.

Humphrey and his allies believed the Democratic platform had to match, if not exceed, the support for civil rights expressed by the Republicans at their convention several weeks earlier. A group of big-city Democratic bosses, not generally known for their liberalism, were predicting ruinous losses in down-ballot races if the party could not galvanize Black voters.

Thus fortified, Humphrey moved to the microphone. In addition to his signature aphorism about shadow and sunlight, and warnings against American hypocrisy on race amid the Cold War, the speech contained a late addition made by a Minnesota political activist named Eugenie Anderson: a sentence commending Harry Truman for his own stand on civil rights. Voting for the civil-rights plank, then, was only endorsing exactly what the president already wanted.