Fifty years ago this month, Aretha Franklin was in the prime of her career. “Think” had just finished a three-week run atop the Billboard R&B charts— her third song of the year to achieve that feat—while her album Lady Soul sold more than one million copies in the U.S. alone. Franklin's notoriety and fame made the singer an ideal choice to open the 1968 Democratic National Convention in Chicago, even amidst violence in the streets and absurdity within the International Amphitheatre, where Yippies attempted to nominate a pig for U.S. president.

The Convention officially opened Monday evening, Aug. 26, 1968. Less than 24 hours earlier, riot police had moved in on protestors who had spent weeks camped out in Lincoln Park preparing for the event, throwing tear gas into the crowd. TV news coverage was spotty due to an electrical workers' strike, and so Franklin's ceremonial performance of “The Star-Spangled Banner” that began the festivities was mostly observed only by those listening on the radio; as recently as 2014, a scholar who wrote a book about the U.S. national anthem believed no video of it existed.

But video does exist, and here it is:

By modern standards, the only noteworthy aspect of this is that Franklin struggled with some of the lyrics in the final stanza. But in 1968, her interpretation caused immediate scandal—setting the tone for what is still remembered today as the most violent and controversial presidential nominating convention in U.S. history.

“She crucified the song and tore my heart to shreds,” wrote the St. Clair Chronicle's H. Denis Moore, one of many to decry her performance with (in their minds) the epithet of “Soul Music.” Indianola, Miss. Enterprise-Tocsin editor David M. Schuller declared that “the National Anthem was tossed around as so much garbage when ‘soul sister’ Aretha Franklin jazzed it up beyond the realm of the musicians...” in a racist essay about “so called good Southerners who have fallen in with this group of radicals.”

The Lexington, Ky. VFW fired off a telegram to the Democratic Party deploring Franklin’s “bop-style singing,” calling it “disgraceful.” U.S. senator Ernest F. Hollings—himself a Democrat—told reporters the performance “repulsed a lot of South Carolinians” in his home state. New York Times TV critic Jack Gould stated Franklin's rendition "put the confusion and undertone of gloom at the convention into prompt focus," while the Daily News's Kay Gardella wrote that it was "objectionable." UPI’s Rick Du Brow declared it “nerve-shatting,” which we’d assume is a typo, but it was left uncorrected in most papers that syndicated his column.

Readers flooded their local newspapers with complaints as well. “Disgraceful and entirely unnecessary,” wrote one; “She jazzed up the singing of it in such a manner that surely made the blood of every true American who heard it boil,” wrote another. “‘Soul’ has its place—where, I’m not sure—but certainly not in the performance of our country’s Anthem,” wrote one Edward C. Goldhill Jr. of Pensacola, while a Warrington, Fla. resident declared that the song had been “degraded and subjected to sacrilege” before continuing: “Yes, give Negroes their rights and opportunities, but let us first be certain they have adequate training and instruction, so that their actions will not be a disgrace and humiliation to all Americans.”

Several common threads emerge from the complaints by a range from national columnists to small-town letter-writers: first, the scare-quotes around “Soul” (or more coded words like “jive” or “bop”), and the implication—in some cases more overt than others—that the “disrespect” shown by Aretha Franklin to this nation's flag, its anthem, and indeed the country itself was representative of the Democratic Party’s (or, alternatively, African Americans’) attitudes toward the same.

We all know what happened over the course of the next several days: while a contentious nominating process happened inside the International Amphitheatre’s walls, the nation's largest and most visible protest against its foreign and domestic policies took place outside them. Vice President Hubert H. Humphrey eventually earned his party's nomination, one that would see the Minnesotan routed by Nixon and, in five Southern states, George Wallace.

It’s possible Franklin’s performance would be better remembered today if not for another person of color performing his own controversial rendition of the song months later, on a much bigger stage. José Feliciano’s Latin-jazz “Star-Spangled Banner” before Game 5 of the World Series in Detroit that October stoked more nativist fears about the corrupting of tradition; the audio recording, released as a single by RCA, spent five weeks on the Billboard charts.

Ten months after that, Jimi Hendrix shredded his electric guitar version at Woodstock, and “The Star-Spangled Banner” was officially open for interpretation.