I have a pet theory to do with Don Siegel’s 1956 paranoid classic, Invasion of the Body Snatchers. It’s that you can interpret the alien pods – pods that will assimilate and annihilate their human hosts – as stand-ins for the TV. During the 1950s the production and sale of TVs in America was rising exponentially, and the sight of neat, suburban houses taking delivery of the new medium would have been curiously analogous to what we see in the film where, with the aliens now dominant, pods are being delivered by the truckload to sleepy Santa Mira.

For the makers of cinema like Don Siegel, the threat of the TV would have been obvious enough, just as the notion of ‘free online content’ would one day send shivers down the spines of print journalists. But there was a period in the 1950s and 1960s when, like the internet in the 1990s, no one was quite sure what TV was for, what its possibilities were and what its limits might be. Like all new technologies, it spawned primitive fears, but with the launch of the Telstar satellite in 1962, it also promised a degree of connectivity hitherto unknown in human history.

When Haskell Wexler came to write and direct Medium Cool in 1968, government institutions were still inclined to underestimate the TV’s social and cultural impact. Journalists reporting from Vietnam had easy access to the military and pretty much free reign in combat zones – Dispatches, Michael Herr’s book about this period, talks of using military helicopters like taxis. It was only after the authorities saw how the gruesome footage being brought back was playing on the evening news that the penny started to drop. (Such freedom of movement would never come again. For professional journalism, the future of TV war reporting was to be embedded, heavily censored, CGI-infused and mostly compliant.)

Medium Cool is both a product of, and commentary on, this period when TV’s status remained uncertain. On the one hand, the new horizons opened up by the medium were already beginning to coalesce around certain systematized procedures, particularly when it came to news broadcasting. On the other, extensive and mostly unsupervised access to military and political institutions was still possible. This curious contradiction was fertile ground for the type of film Wexler wanted to make, one that would combine social documentary and fiction in a kind of Godard-inspired cinéma vérité. It tells the story of cameraman John Cassellis, played by Robert Forster, who is working for a TV station in Chicago leading up to and including the riots surrounding the Democratic National Convention in August. It’s a vaguely autobiographical portrait of Wexler himself.

In an interview Wexler says, “History is written by the people who hold the pens, the typewriters, the printing presses, the movie cameras, the TV cameras. In 1968 in America, history was being written by people who were ignoring history. I decided to make a film which reflected this energy which I felt so passionately about.”

And in 1968 there was plenty to be passionate about. It was an election year, for one thing, which in March saw the sitting president, Lyndon Johnson, resign his candidacy over Vietnam and the violent escalation that had occurred with the Tet Offensive. In April, Martin Luther King was assassinated in Memphis, provoking riots in black ghettos across the country. Two months later, after winning the California primary and establishing himself as a viable Democratic prospect for the presidency, Robert Kennedy was assassinated. All of this fed into the febrile, paranoid atmosphere that had been building since John F Kennedy was assassinated in 1963, especially among those quarters of the counter-culture that had been steadily pickling in dope and acid for close to a decade now.

The perfect storm then, and so it proved to be. In fact, Wexler was so convinced things would kick-off in Chicago when the Democratic Convention rolled into town, he’d worked it into his script months earlier. The authorities also smelled a millenarian whiff in the air, the reason why early on in the film we get footage of the Illinois Army National Guard involved in a real exercise preparing for civil disturbances. It’s a surreal scene, typical of the way the film permeates the boundaries and blurs the lines between what is real and what is staged. Members of the real army dress up as fake protesters, some in full hippie garb, while other soldiers in combat fatigues work out real strategies for containing them. Meanwhile, John Cassellis is here filming fake footage for a fake news piece while Wexler shoots the live film.

The scene is also one of many in Medium Cool where violence and how it is mediatised is put under scrutiny. We’re confronted with it even in the pre-credit sequence as John and soundman Gus (Peter Bonerz) arrive at a car crash, dispassionately going about their trade while the female driver lies moaning in pain. A little later, they’re among real TV journalists who are talking about this aspect of their jobs. In response to suggestions of gratuitousness, one of them says, “The big bombs [in terms of ratings] were the ones where we went into detail and showed why something happened. Nobody wants to take the time. They’d rather see thirty seconds of someone getting their skull cracked.”

Various media theorists have speculated on why TV news seems so wedded to violent content. Obviously it’s exciting and appeals to the dynamic nature of the medium – the spectacular aspect of it – as well as to evolutionary conditioning in human beings like the fight or flight reflex. Except, of course, when you’re watching violence on TV, there’s no flight involved, quite the opposite. Like John and Gus at the car crash, we’re rubbernecking. This daily diet of disasters has a further effect, namely to reinforce the perception that death is elsewhere, that it belongs primarily among the poor and the ghettoized.

The film’s title is taken from Marshall McLuhan, the media theorist du jour, although it wasn’t Wexler’s suggestion and he freely admits he can’t understand the first thing about McLuhan’s writing. The film nevertheless contains plenty that you might call McLuhanesque: the medium itself frequently made present in the minds of the audience, put under examination every bit as much as the content being recorded. McLuhan himself had very little time for content, arguing it’s like “the juicy piece of meat carried by the burglar to distract the watchdog of the mind.” What the medium is really doing, he says, irrespective of what we’re actually seeing on it, is working deep on our nervous systems and fundamentally remoulding consciousness.

Even stranger and more contentious is the theory forwarded by writers like Friedrich Kittler and Manuel De Landa that, given most media technologies have their origins in warfare, this violent heritage is somehow written into their DNA, haunted by it, if you will, like malevolent ghosts in the machines. There’s a flavour of Philip K Dick paranoia to this, but it is curious, and a little unnerving, to discover that the radio relates back to battlefield communications technology, the cinematograph to the machine gun, TV to radar, and the computer to military encryption. Even the internet was in part a product of the ARPANET, a military project designed to link defense computers together into a sealed network. At any rate, it’s a reminder that whatever else media technologies might be, they’re created out of a particular set of historical circumstances and their use is dictated by those circumstances. You can’t have a totalitarian state if you can’t control the media, for example.

What’s certainly true is that among poor, ghettoized blacks in Chicago in 1968, there was an acute awareness of the power of the TV to shape reality. In one extraordinary scene in Medium Cool, black militants speak directly to the camera. It’s ambiguous as to whether we’re supposed to see them as addressing John Cassellis’s camera or Wexler’s but the effect remains the same – they’re talking to us. And what they’re talking about is being exploited by TV media. “You are the ones who distort and ridicule and emasculate us,” says one. Another argues that the only way for a black man to get on TV is by committing an act of violence. “He takes a gun and he shoots. And you make him the TV star of the hour. Because a hundred million people see him on the tube. So the former invisible man lives.” The TV brings him into history, but because it’s a media controlled by the dominant caste, he can only enter history in this negative guise.

The apparent indifference of John Cassellis to the implications of his profession is reflected in the first third of the film. He inhabits the surface of things, enjoys casual relationships, enjoys the theatrical violence of the roller game. This begins to change when he crosses paths with a boy, Harold (Harold Blankenship), an actual street kid from Chicago. It leads him to the slum tenements of the Appalachian community, opening up another thread in the film, the plight of disenfranchised southern whites. These people were living in conditions every bit as desperate as the black community, suffering in the same way, and it saw the establishment of joint black and white movements such as the Poor People’s Campaign – the film includes a sequence of Cassellis in Washington wandering around Resurrection City, the shantytown that took up residence in the National Mall.

John begins a relationship with Eileen (Verna Bloom), the boy’s mother, whose job actually involves assembling TVs for Motorola, which given the context is a bit like prisoners making their own leg irons. Time among the tenements forces Cassellis to become more socially aware. Soon he discovers that his TV station has given film footage he took of people burning their draft-cards to the FBI. Then he finds himself mysteriously fired after trying to pursue a story about a black taxi driver who handed in $10,000 to the police that he found left on the back seat of his cab. Watching a TV special on Martin Luther King after the civil rights leader’s assassination, Cassellis is quick to read the subtext: “The media’s got a script now. Memorial meetings. Memorial marches. People are afraid the Negroes are going to burn neighbourhoods, so they have this nationwide, coast-to-coast network special called ‘Mourn the Martyr’. Nobody’s really on the hook. But when the script is finished, everybody goes pretty much back to normal.”

Normality, in its way, had found the hippies by 1968, at least to the extent that their looks and mannerisms had been assimilated into the consumer culture. In the psychedelic ‘America is Wonderful’ sequence, they get pretty short shrift, with Frank Zappa’s ‘Who Need’s The Peace Corps?’ front and centre as people dance inanely amid strobes, liquid projections and dissolving light gels. Meanwhile, the Yippies under the direction of Abbie Hoffman and Jerry Rubin, and with a much shrewder sense of the power of the media, had for some time prior to the Convention been advertising their plans to prank The System, most famously the tongue-in-cheek suggestion to dump LSD into the city’s water supply. But such was the tension and paranoia now pervading everything like a smog, few could be sure what was a joke and what a threat, least of all the authorities.

So by the time the Democratic Convention came around, the powers-that-be had 6,000 Regular Army troops in full field gear, equipped with rifles, flame-throwers and bazookas, as well as 6,000 Illinois Army National Guard (the same outfit that appeared in the fake riot now coming for the real one) and 12,000 members of the Chicago police force conditioned to expect violence and given carte blanche in containing it. If you’ve ever had the uncanny sensation an ‘invisible coup’ has taken place in your country, and the only time you realize it has taken place is when its instruments of power are forced to surface in order to defend it, then Chicago in August 1968 seemed apt confirmation. “Here we have an army at war with its people,” says Wexler.

In the absence of rioting, the police eventually decided to have one of their own, and in the final scenes of the film Eileen, in her bright yellow dress, is picking her way through cops working their nightsticks, combat units marching on Downtown streets and rows of military jeeps parked outside the city’s museums. Eileen is fictional, yet everything going on around her is not. Meanwhile, John Cassellis is at the International Ampitheatre with his camera, filming the delegates of the Democratic National Convention as ‘Happy Days Are Here Again’ rings out over the sound system. Again, Cassellis is fictional, but everything going on around him is not.

By using fiction, Wexler finds his way to truths that documentary alone cannot reach, and by using documentary, creates an atmosphere and authenticity no work of fiction can ever recreate. In a world now girded by media satellites and dominated more than ever by the proliferating fictive fabrications coming from our screens, Medium Cool resonates because it still has a greater share of historical reality than the bulk of what fills these screens today.

“The whole world is watching” chant the protesters at the end of the film, and as they do, we get a shot of Wexler turning his camera on us, as if to say, “so what are you going to do about it?”

Medium Cool is out now on DVD and Blu-Ray from Eureka!