Chicago Police attack a march of steelworkers and their families, May 30, 1937. Photo National Archives and Records Administration

A major labor strike is back on the front pages this week, as Writers Guild members—movie and TV writers—have walked out. The most obvious fallout so far: late night talk shows going dark or struggling for jokes. Stephen Colbert, before signing off on CBS for who knows how many weeks, did declare: “This nation owes so much to unions.”

Labor actions and organizing, in fact, have been surging in recent years, mainly in new industries, from Starbucks to Amazon and Apple.

Decades in the past, strikes often led to violent conflict between workers and local police. It virtually never happens today. This is at least partly due to what happened eighty-six years ago this month in Chicago, after police shot forty steel strikers and supporters (mainly in the back) and killed ten of them in what has become known as The Memorial Day Massacre. No labor conflict has come close to this toll since.

Nevertheless, Paramount buried the only footage of the incident, until a famed reporter and crusading U.S. senator brought it to light.

My new film exploring all this premiered over PBS on May 6. It’s titled Memorial Day Massacre: Workers Die, Film Buried. It will be aired over local PBS stations all month but everyone can watch it starting the same night and for several weeks after via PBS.org and PBS apps, or at the site for the hosting station, KCET in Los Angeles.

It’s also explored my companion book of the same title, the first oral history on the tragedy, with testimony from eyewitnesses as well as historians and authors such as Howard Zinn, John Hope Franklin, Gore Vidal, David Kennedy and Studs Terkel, and even Ayn Rand.

The background: A wave of labor actions swept America starting in 1935. Sit-down strikes became all the rage and even General Motors and Ford caved. The largest steel company, U.S. Steel, avoided a strike by offering workers--under pressure from new CIO chief John L. Lewis--but companies known as Little Steel (though hardly small) across the Midwest and Pennsylvania, refused to even recognize the new Steel Workers Organizing Committee.

More than 70,000 at those plants declared a strike in late-May, 1937. When some set up picket lines outside Republic Steel in South Chicago, police swung nightsticks and more than two dozen were injured. So they scheduled a family picnic to mobilize support on a broad field several blocks from the Republic plant on May 30. Well over one thousand turned out on this hot, sunny day, including many women and children, dressed in their Sunday best. Organizers called for a ragged march to the plant for legal, mass, picketing.

When they were halted by hundreds of Chicago police, armed with pistols and some carrying axe handles or tear gas provided by Republic, a few minutes of heated discussion ensued. Some marchers tossed stones or a tree branch, and police lost patience with the crowd, which included women and children, when they failed to disperse as ordered. Suddenly police hurled tear gas bombs and then fired dozens of shots.

About 40 marchers would be shot as they fled across the open prairie, including an 11-year-old boy, the vast majority wounded in the back or side. (Ten would die that day or in days ahead.) Dozens more would suffer head wounds after police clubbed the retreating marchers.

Police did not call ambulances or administer first aid but instead arrested the wounded and shoved them into paddy wagons for trips to a prison hospital and other distant medical facilities. Only a handful of police suffered injuries, all minor.

Newspapers across the country (including The New York Times) almost invariably described the marchers as a “mob” of “rioters” who left no choice but for police to fire shots to keep them from attacking the plant. After two weeks of this, it emerged that a leading newsreel company, Paramount News, had a cameraman on the scene. He had filmed almost the entire confrontation and ugly aftermath. But Paramount failed to release the four-minute newsreel it prepared, claiming they feared it might set off riots in movie theaters, but more likely to protect Chicago police and officials.

This sparked a Senate subcommittee, under the Wisconsin progressive, Robert M. La Follette, Jr., to subpoena the footage. A staffer leaked it to investigative reporter, Paul Y. Anderson, who wrote a sensational report picked up by many newspapers. At the well-publicized hearings called by La Follette at the end of June the footage was screened for the first time.

Paramount now had little choice but to release a newsreel devoted to the incident. Screenings, however, would be banned in cities such as Chicago and St. Louis, or by entire theater chains. The Senate report would place full blame on police for the massacre. Yet a coroner’s jury in Chicago would judge the killings “justifiable homicide.” No police would be punished. Dozens of unionists had been wounded, jailed or fined.

Workers at the steel plant returned to the plants without a contract, but they would win recognition and most of their demands a few years later. And there was this positive result: Strike leaders in nearly every field now tried to avoid violent conflicts at all cost and police were determined to control labor actions without the use of firearms.

Today, police shootings of unarmed citizens remain far too common, and often unpunished. But there is this further legacy of 1937 massacre: It provoked the first calls for police to be equipped with cameras to document arrests—anticipating the dashboard-cams and body-cams that reveal so many of the unjust shootings today.

PBS is now streaming this documentary.