As the political actors of South Carolina move to eliminate the Confederate flag from their state Capitol grounds in the wake of the mass murder carried out by a white supremacist at a historic black church, one legislator in particular made news with his speech calling for the flag to come down: 39-year-old Republican state senator Paul Thurmond, who delivered a blunt assessment of the flag claimed by many as a symbol of Southern “heritage” — and, in doing so, personally illustrated the vast cultural shifts that have occurred.

“For the life of me, I will never understand how anyone could fight a civil war based in part on the desire to continue the practice of slavery,” Thurmond said.

“Think about it for just a second: Our ancestors were literally fighting to continue to keep human beings as slaves, and continue the unimaginable acts that occur when someone is held against their will. I am not proud of this heritage. These practices were inhumane — and were wrong, wrong, wrong.”

He concluded, “I am proud to be on the right side of history regarding the removal of this symbol of racism and bigotry from the statehouse” — but also said that the state must not stop there, and needed to “start a different conversation” on the healing of race relations.

And with this momentous speech, Thurmond also turned a new page in his own family’s history, taking a big step away from the political legacy of his father, the late U.S. senator Strom Thurmond, who built much of his career — and even helped reshape the Republican Party when he switched his affiliation in 1964 — on fighting against civil rights.

Strom Thurmond infamously ran for President of the United States in 1948, with a campaign based squarely on state racism — even threatening massive, violent resistance. And in that year he delivered a stump speech that was sharply distinct from the one his son delivered Tuesday.

“There’s not enough troops in the Army,” the elder Thurmond proclaimed, “to force the Southern people to break down segregation, and admit the n****r race into our theaters, into our swimming pools, into our homes, and into our churches!”

The tone of that speech, and that campaign, spoke to the revolutionary changes that were happening in the nation’s political parties.

In the 1948 election, with President Harry Truman widely seen as an underdog, he and many establishment Democrats hoped to paper over the party’s divides at the national convention. In an attempt to appease the South, they had proposed a weak civil rights platform that fell short of recommending any specific federal legislation.

Northern liberals, led by Minnesota’s Hubert Humphrey, struck back on the convention floor by successfully passing a strong civil rights plank — a key moment in political history, when the Democratic Party effectively repudiated its institutional history, dating back to the 19th century, of opposition to the rights of African-Americans.

Humphrey’s speech for the alternative proposal is best known for this memorable quote:

To those who say that we are rushing this issue of civil rights, I say to them we are 172 years late. To those who say that this civil rights program is an infringement on states’ rights, I say this: The time has arrived in America for the Democratic Party to get out of the shadows of states’ rights — and to walk forthrightly into the bright sunshine of human rights.

The success of Humphrey and the northern liberal Democrats so outraged the southern conservatives in the party that a group of them bolted from the Democratic convention to hold their own in Oklahoma City. Running as the “States’ Rights Democratic Party” — commonly known as the “Dixiecrats” — they nominated South Carolina governor Strom Thurmond on the unabashed platform of strident white supremacy.

The Dixiecrat platform itself proclaimed:

We stand for the segregation of the races and the racial integrity of each race; the constitutional right to choose one’s associates; to accept private employment without governmental interference, and to earn one’s living in any lawful way. We oppose the elimination of segregation, the repeal of miscegenation statutes, the control of private employment by Federal bureaucrats called for by the misnamed civil rights program. We favor home-rule, local self-government and a minimum interference with individual rights.

We oppose and condemn the action of the Democratic Convention in sponsoring a civil rights program calling for the elimination of segregation, social equality by Federal fiat, regulations of private employment practices, voting, and local law enforcement.

Thurmond carried four Southern states — South Carolina, Alabama, Mississippi, and Louisiana — where on a large scale African-Americans were unconstitutionally prevented from voting. (Truman still won the national election — helped in part by gaining black voters in the North, with the Democratic Party now officially committed to civil rights, and Truman having just issued an executive order to desegregate the military.)

At the time Strom Thurmond delivered these speeches and ran on this platform of “racial integrity,” he well knew that he had a secret African-American daughter, named Essie Mae Washington-Williams, whom he had first met in person some time around 1941 or 1942.

Washington-Williams publicly announced her parentage in 2003, shortly after Strom Thurmond died, detailing how he had financially supported her and met with her over the years. She was in turn acknowledged by the rest of the Thurmond family after the announcement.

Washington-Williams passed away in 2013 at the age of 87, but in the intervening time she had also met personally with some of her white relatives — including her much younger half-brother, Paul Thurmond.