On July 27, 1919, a white man hurled rocks at 17-year-old Eugene Williams, a Black boy who’d drifted into an unofficially “white” section of a Chicago beach. Williams was floating on a raft and the pelting caused him to slip off and drown. When police refused to make an arrest, outrage led to protests and a week of rioting as white Chicagoans responded in violence.

Over the next several days, rioting broke out between gangs of Black and white Chicagoans, concentrated on the South Side neighborhood. By the time the violence ended on August 3, 15 white and 23 Black people had been killed and more than 500 people were injured. Some 1,000 Black families also lost their homes when they were torched by rioters. Later that summer, The New York Times claimed the real cause of the unrest was “Soviet influence.”

This was a common conspiracy theory to find in northern white newspapers during the “Red Summer,” a period between roughly April and November 1919 in which “race riots” broke out in at least 18 states and Washington, D.C. White mobs instigated most of these riots, and Black Americans—who’d just served their country in World War I and were tired of unequal citizenship—fought back. Among white Americans, communism became a convenient scapegoat.

This was during the country’s First Red Scare. Two years before, Bolshevik Party leader Vladimir Lenin had led a coup d’état to establish communist rule in Russia, which became the Soviet Union. In the United States, unions like the Industrial Workers of the World, or IWW, were championing workers’ rights by leading strikes around the country.

In March 1919, the Communist International, or “Comintern,” formed with the intent to spread communism around the world. And over the next two months, anarchists began sending mail bombs to prominent figures like U.S. Attorney General A. Mitchell Palmer.

In the midst of this, some white Americans feared communists and other perceived “radicals” were trying to overthrow the United States by sowing racial unrest so Black Americans would riot.

Underpinning this conspiracy theory was the assumption that someone must be egging on Black Americans to protest. Representative James F. Byrnes of South Carolina claimed the average southern Black man was “happy and contented and will remain so if the propagandist of the I.W.W., the Bolsheviki of Russia, and the misguided theorist of other sections of this country will let him alone,” according to the Congressional Record for August 25, 1919.

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Byrnes suspected the IWW was financing a magazine called The Messenger in order to spread anti-American messages, and he demanded the U.S. government prosecute the magazine under the 1918 Sedition Act.

Mark Ellis, a senior lecturer in history at the University of Strathclyde in Glasgow who has written about the Red Summer, says part of what was going on was that people like Byrnes thought Black Americans “couldn't be producing such articulate, well-produced, slick journalism as you would see in The Crisis magazine and The Messenger magazine.”

“I think deeply racist officials, who didn’t seem to believe that Black people are capable of doing this sort of thing and coming up with these ideas and these arguments on their own, simply assumed that they were being put up to it.”

There was never any proof that communists or other supposed political radicals were influencing Black publications or convincing Black Americans to riot, but the theory didn’t need proof to thrive. The conspiracy theory was similar to a previous one involving a WWI German spy scare. When the United States entered the war in 1917, many white Americans saw Black activists’ and soldiers’ campaigns for equal rights as evidence of German subversion.

“The idea of ‘pro-Germanism among the Negroes’—which is how military intelligence headed its reports—really spreads [during the war],” Ellis says. “There’s all sorts of briefings given to newspapers like The New York Times about German infiltration and various sorts of plots without any facts to back it up. I think a lot of people simply believed that it was just a straightforward fact that Germans were trying to subvert the loyalty of Black Americans, and were being quite successful.”

Paranoia about Black people resisting white rule goes back even further, to when white southerners feared slave revolts, says Cameron McWhirter, author of Red Summer: The Summer of 1919 and the Awakening of Black America.

“I think there was always a concern in American history by some whites that African Americans were plotting against them,” McWhirter says. “The rise of the Bolsheviks and the collapse of Russia, the rise of anarchism and anarchists leaving bombs at people’s doorsteps in 1919, really fueled this notion that…somehow [the Red Summer] was linked to these radical movements.”

This conspiratorial thinking influenced how Attorney General Palmer and a young J. Edgar Hoover responded to the Red Summer. In August 1919, 24-year-old Hoover became chief of the new General Intelligence Division or “Radical Division” within the Bureau of Investigation (an early version of the FBI). In this new role, he instructed his agents to search for communist influence in the Red Summer riots, hired a Black agent to infiltrate Black activist groups and fed the media false stories about radical influence.

Even though Hoover’s agents consistently failed to find evidence of this influence, Hoover continued to promote the conspiracy theory. That fall, he published a report called “Radicalism and Sedition Among the Negroes as Reflected in their Publications,” which white newspapers used as evidence that communists and other political radicals were behind Black magazines and newspapers that questioned the racial status quo. (The report, written by a Post Office worker without attribution, did not actually prove a connection.)

This type of thinking didn’t just go away after 1919. A few decades later, white officials practically recycled the Red Summer communist conspiracy theory during the civil rights movement. In 1963, Alabama Governor George Wallace told The New York Times that “President [John F. Kennedy] wants us to surrender this state to Martin Luther King and his group of pro-Communists who have instituted these demonstrations.” And throughout the south, billboards purported to show a picture of King “at communist training school.”

Hoover’s own paranoia about communism and Black activists during the Red Summer of 1919 also influenced the way he targeted King and other civil rights leaders in the 1950s and ‘60s. As director of the FBI, he argued that these leaders were being influenced by communists, and authorized a series of illegal wiretapping and harassment campaigns against them.

“There’s a bit of tendency throughout American history to attack people who you don’t like for their alleged disloyalty, and it’s a way of avoiding engaging with the point they’re actually making,” Ellis says. “You don’t need to prove it in order for it to be effective, and I think that’s something that Hoover found.”