Eugene Debs had led historic strikes and run for president four times on the Socialist Party ticket, But the renowned orator had never given a speech so risky or consequential as the one he delivered in a Canton, Ohio, park on June 16, 1918.

As 1,200 people watched, Debs stepped to the front of a wooden bandstand. Nearly bald, he wore a tweed jacket and buttoned vest despite the summer swelter. Justice Department agents sifted through the audience, asking to see men’s draft cards. As Debs spoke, a stenographer hired by a federal prosecutor took frantic notes of the lines that struck him as especially subversive. Sweat dripped down Debs’ face, and his arms reached over the bandstand’s rail toward the crowd.

“The working class have never yet had a voice in declaring war,” Debs declared. “If war is right, let it be declared by the people – you, who have your lives to lose.”

Those were dangerous words in June 1918. World War I was nearing its climax, with American soldiers fighting their first major battles, resisting Germany’s all-out drive toward Paris. The U.S. government, armed with repressive new laws, had jailed anti-war protesters across the country. And Debs, 62 years old and recovering from illness, had emerged from near-seclusion to rejoin the fight against the war.

“Debs Wakes Up Howling At War; U.S. May Get Him,” a Chicago Tribune headline announced the next day. “Debs Invites Arrest,” the Washington Post declared. Soon Debs would be in jail for his speech that day. His trial and incarceration would captivate the tense, conflicted nation. After the war, Americans debated whether he was a traitor or a martyr for free expression. Debs’ Canton speech, delivered 100 years ago this week, became the era’s most infamous example of how dissent can become a casualty of war.

Debs’ journey to that stage in Canton began in 1870, when he left his hometown of Terre Haute, Indiana, at age 14 to work in train factories. “From my very boyhood I was made to feel the wrongs of labor,” he wrote in the New York Comrade in 1904: the dangers, uncertainty of work, and scant wages common to working men. After years in the labor movement, he became president of the new American Railway Union in 1893.

Sentenced to jail for helping to lead the 1894 Pullman railroad strike, he spent six months behind bars educating himself with the works of Karl Marx, among others. He declared himself a socialist in 1897, helped found the Socialist Party of America in 1901, and ran for U.S. president on Socialist tickets in four straight elections, starting in 1900.

An inspiring speaker, he drew thousands of fervent supporters to rallies in major cities, while inspiring equally fervent denunciations by mainstream politicians and newspapers. Theodore Roosevelt called Debs one of the nation’s most “undesirable citizens” and accused him of fomenting “bloodshed, anarchy, and riot.” Debs’ argument that workers should own the products of their labor was too radical for most Americans. Yet Debs presented socialism in ways that appealed to Americans’ cultural and religious values. He shocked the political system by winning 900,000 votes, or 6 percent of the vote, in the 1912 presidential election, more than Ralph Nader in 200 or Gary Johnson and Jill Stein in 2016. Debs had a “profoundly intuitive understanding of the American people,” wrote historian Arthur Schlesinger Jr. “Men and women loved Debs even when they hated his doctrine.”

When World War I broke out in Europe in August 1914, Debs joined the movement to preserve American neutrality. Early in the war, most of the nation, from conservative isolationists in the Midwest to liberals in the East, wanted to stay out of Europe’s war. Although many Americans agreed with Debs on the merits, fewer aligned with his socialist critique of entering the war. It was a battle between the ruling classes of the warring nations, he argued – and in fact, an economic critique of the war, which notes that the U.S. profited from trade with Britain and wartime loans to the Allied powers, persists among historians today. “I know of no reason why the workers should fight for what the capitalists own,” Debs wrote to novelist Upton Sinclair, “or slaughter one another for countries that belong to their masters.”

In March 1917, as news of the Zimmermann Telegram pushed the U.S. toward war, Debs toured the Northeast, arguing for peace to crowds of thousands. “I will never go to war for a capitalist government,” Debs declared. “I will never go to war for a capitalist government,” Debs declared. Congress’ declaration of war against Germany in April did not deter him. “Debs doesn’t believe that government is really representative of the people,” says Nancy Unger, a historian at Santa Clara University and author of several books on 1910s America. “It’s controlled by money and issues of power.”

Meanwhile, President Woodrow Wilson’s Democratic administration launched an intense propaganda effort to bolster support for the war, along with one of the most aggressive campaigns of political repression in U.S. history. Empowered by the Espionage Act, passed by Congress in June 1917, the government blocked the mailing of anti-war newspapers and arrested 2,000 protesters on charges of inspiring resistance to military recruitment. States passed sedition laws and arrested dissenters. The American Defense Society, a right-wing vigilante group, pulled anti-war speakers off soapboxes in New York City. The American Protective League, a national group of 250,000 volunteers acting with the blessing of U.S. Attorney General Thomas Gregory, searched their neighbors’ homes and mail and reported the allegedly disloyal.

“Wilson couches it in Progressive-style terms: a war to make the world safe for democracy,” says Unger. “If you’re against that, you’re un-American, you’re selfish, you’re wrong. The same statements Eugene V. Debs has been making his whole life are now not just on the left of the political spectrum. He’s now presented as dangerous, un-American, a saboteur.”

Debs protested censorship in his opinion columns in socialist newspapers such as Social Revolution , but as the war continued, the government shut down many papers that printed his writing. Illness slowed Debs for several months after war was declared; he mostly stayed home in Terre Haute, resting under doctor’s orders, sick with back pain, digestion problems, and a weak heart. But in December, his friend Kate O’Hare, the nation’s most prominent female socialist, was convicted under the Espionage Act for a July 1917 anti-war speech and sentenced to five years in prison. “I shall feel guilty to be at large,” Debs wrote her in solidarity. In May 1918, Congress passed the Sedition Act, further tightening restrictions on dissent.

Enraged, Debs set out in June on a new speaking tour of the Midwest. He knew he was courting prosecution, and maybe even welcomed it. “I’ll take about two jumps and they’ll nail me, but that’s all right,” he told a friend. He barnstormed Illinois and Indiana, speaking against the war without incident, before he headed to Ohio for the state Socialist convention in Canton.

Before speaking at the convention picnic, Debs visited the nearby Stark County Workhouse, where three Ohio Socialist leaders were serving one-year sentences for opposing the draft.

“Three of our most loyal comrades are paying the penalty of their devotion to the cause of the working class,” Debs told the crowd. “They have come to realize,” he added, “that it is extremely dangerous to exercise the constitutional right of free speech in a country fighting to make democracy safe in the world.”

For two hours on the bandstand in Canton, Debs defended imprisoned anti-war activists from accusations of disloyalty. He praised Russia’s Bolsheviks, claiming they’d founded “the first real democracy” when they’d taken power in the Russian Revolution eight months earlier. Denouncing the U.S. Supreme Court for striking down a law against child labor, he declared that socialism would triumph over capitalism. “Do not worry over the charge of treason to your masters,” Debs said. “Be true to yourself and you cannot be a traitor to any good cause on earth.”

Two weeks later, Debs was walking into a Socialist picnic in Cleveland when U.S. marshals arrested him. He was charged with ten counts of violating the Espionage and Sedition acts during his Canton speech.

At Debs’ trial in Cleveland in September 1918, the prosecutor argued that Debs’ speech was “calculated to promote insubordination” and “propagate obstruction to the draft.” Debs’ lawyers conceded the facts of the case, and Debs spoke on his own behalf.

“I have been accused of having obstructed the war,” Debs told the jury. “I admit it. I abhor war. I would oppose the war if I stood alone.” He defended socialism as a moral movement, like the abolition of slavery decades before. “I believe in free speech, in war as well as in peace,” Debs declared. “If the Espionage Law stands, then the Constitution of the United States is dead.”

The jury found Debs guilty on three counts, and the judge sentenced him to ten years in prison. Newspaper editorials across the nation cheered his conviction. “His activities in opposition to the war preparation were dangerous,” the Washington Post declared. “His conviction… serves notice to all that disloyalty and sedition, even though masquerading under the guise of free speech, will not be tolerated.”

Debs’ case went to the U.S. Supreme Court, which ruled in 1919 that expressing sympathy for men who resisted the draft made Debs himself guilty of the same offense. Debs reported to prison in Moundsville, West Virginia, in April 1919. “I enter the prison doors a flaming revolutionist,” he telegraphed his supporters, “my head erect, my spirit untamed and my soul unconquerable.”

The nation’s most famous political prisoner, Debs spent 2½ years at a federal penitentiary in Georgia. After the war, he became the symbol of a growing movement pushing for amnesty for imprisoned radicals. In newspapers and everyday conversation, Americans debated whether to free Debs. “For most Americans Debs embodied the entire controversy,” wrote Ernest Freeberg in his 2008 book on the Debs case, Democracy’ s Prisoner. “He was the only prisoner who had a face and voice, the one who provoked citizens to either defend or oppose their government’s prosecution of wartime dissenters.”

In 1920, the Socialist Party nominated Debs for his fifth run for president. Campaigning from prison, Debs issued weekly campaign statements to the United Press wire service. Rather than debate Republican candidate Warren G. Harding or Democratic nominee James Cox, Debs denounced the lame-duck Wilson as “a tool of Wall Street” and “a college professor who isn’t fit to be president because he doesn’t know the lives of the people.”

As Convict No. 9653, Debs attracted 3.5 percent of the vote for president. “Thousands upon thousands had cast their votes for the prisoner in order to protest the infringements of civil liberties,” wrote Ray Ginger in The Bending Cross, his classic 1947 biography of Debs.

The Wilson administration, unmoved, rejected a recommendation to commute Debs’ sentence in February 1921. “While the flower of American youth was pouring out its blood to vindicate the cause of civilization, this man, Debs, stood behind the lines, sniping, attacking, and denouncing them,” Wilson complained to his secretary. “This man was a traitor to his country."

Harding, who replaced Wilson in March 1921, was more receptive to the amnesty campaign. Freeing Debs and other radical prisoners fit his campaign promise of a “return to normalcy” after the war.

“For Wilson, it really was like a holy war,” says Unger. “I think he really believed

it could be a war to end all war. I don’t think he could ever forgive Debs.” Harding, she says, “certainly did not have the same emotions and moral investment in that war. I just don’t think for him Debs was a threat.”

In December 1921, Harding commuted Debs’ sentence, set his release for Christmas Day, and invited Debs to the White House . “I have heard so damned much about you, Mr. Debs, that I am now very glad to meet you personally,” Harding greeted him on Dec. 26. Leaving the meeting, Debs called Harding “a kind gentleman” with “humane impulses,” but declared that he’d told the president he would continue the fight for his “principles, conviction, and ideals.” He took the train to home to Terre Haute and his wife, Kate, the next day.

Debs died in 1926 at age 70. His Canton speech remains a classic of American dissent -- the actor Mark Ruffalo gave a dramatic reading from it in 2007. He remains a hero to American socialists – including U.S. Sen. Bernie Sanders, who directed a 1979 documentary about Debs and read his quotes in his distinctive Brooklyn accent. “The master class has always declared the wars,” Sanders intoned in a two-minute excerpt from Debs’ Canton speech. “The subject class has always fought the battles.”