In 1968, politics on television changed forever.

During that year’s Republican and Democratic National Conventions, NBC News and CBS News provided comprehensive gavel-to-gavel convention coverage anchored by straight-arrow newsmen like Walter Cronkite, David Brinkley, and Chet Huntley. ABC News could not afford such lavish coverage, languishing as it did a distant third in the nightly ratings. As one observer put it, they would have been in fourth place, but there were only three networks.

So ABC News offered viewers a different kind of convention coverage. After abbreviated summaries of each day’s convention proceedings, ABC capped the day with one-one-one debates between conservative William F. Buckley, Jr., and liberal Gore Vidal.

Those debates are the subject of the fascinating new documentary Best of Enemies.

Buckley and Vidal were two sides of the same coin. Matter and anti-matter. Fire and ice. But both erudite intellectuals. Both passionate ideologues. Both failed politicians. Both savage debaters.

And both hated each other thoroughly and sincerely.

When ABC News first approached Buckley about participating in the nightly discussions, they asked him if there was anyone he would prefer to debate. He told them anyone other than a communist or Gore Vidal.

William F. Buckley, Jr., was the godfather of the modern conservative movement in America. He founded the magazine National Review, the (other) Bible of American conservatism. He palled around with Ronald Reagan. And he hosted the television show Firing Line, in which he personally debated liberals from all walks of life. Buckley saw Vidal as a symbol of the moral decay of society, genuinely considering him and what he represented to be dangerous to the future of America.

To Gore Vidal, Buckley represented the intellectual façade that masked the ugly machinations of the Republican Party and the conservative movement that had seized control of it. By the time they met in 1968, Vidal was a successful author, screenwriter, and liberal cultural warrior. He looked at Buckley and saw bigotry, paternalism, and elitism, and he suspected that for all of Buckley’s intellectual gymnastics, he was driven—like all conservatives, Vidal felt—by greed and avarice and lust for power.

As Best of Enemies documents, once the debates began, it became clear almost immediately that Buckley and Vidal were largely uninterested in debating the events of the day and only slightly more interested in debating the broader policy questions that would shape the coming Presidential election. Instead, their aim night after night became to ridicule the other, to undermine and attack each other’s intellectual and moral foundations, and to completely discredit not only each other, but by proxy the ideological movement that the other represented.

The documentary demonstrates how Vidal came to the debates armed with opposition research, scripted and rehearsed “spontaneous” retorts, and a strategy to grate, irritate, and bait Buckley in order to “expose” him to a mainstream, national audience.

And his strategy worked.

Over the course of the debates, snide asides became pointed barbs, which evolved into personal insults, which exploded into a dramatic, riveting exchange in which Vidal taunted Buckley as a “crypto-Nazi” and Buckley spat back his infamous, defining invective: “Now listen, you queer, stop calling me a crypto-Nazi, or I’ll sock you in your goddamn face and you’ll stay plastered.”

The live-TV exchange was jaw-dropping at the time, and nearly 40 years later, the documentary’s juxtaposition of images of the trembling-with-anger Buckley and the smug, self-satisfied, grinning Vidal completely and utterly enthralls.

At the heart of Best of Enemies, though, is not just the story of two men, ten debates, and a few weeks in 1968.

The Buckley-Vidal debates set in motion a change in televised political coverage that has never been reversed and that now defines the way Americans consume their political news…and really their politics in general.

ABC’s ratings soared during the 1968 Party Conventions, and never again did any network provide full gavel-to-gavel convention coverage. Commentary began to dominate political news, later giving rise not only to the take-no-prisoners formats of broadcast network shows like Meet the Press, cable programs like Crossfire, and even whole networks like Fox News and MSNBC.

The seeds of the Buckley-Vidal debates flowered well beyond politics, in fact. Today, television, radio, and internet pundits shout angrily at each other daily about the latest sports news, the direction of the stock market and the economy, and even about the latest foibles of the least important celebrities.

Even more significantly, though, the glimpse into the Buckley-Vidal debates offered by Best of Enemies is striking in its implications for how people who disagree today feel not only about the issues that they debate but also about the people on the other side of the aisle. It is no longer enough to discredit someone’s argument or to rhetorically triumph through logic or reason. Rather, victory can only be achieved by discrediting the other guy, the other Party, or the other movement. Absent the ability to prove the supremacy of any particular ideological value beyond a reasonable doubt, it is much easier to attack motives, to question morals, and to damn messengers.

None of that, of course, can entirely be traced to the Buckley-Vidal battles, but that brief moment in political history—and the window into it provided by Best of Enemies—certainly offers an absorbing look at what we have all become.

As for Buckley and Vidal themselves, Best of Enemies submits that in two lifetimes of tremendous achievement, their battles in 1968 were defining personal moments.

For decades afterward, Vidal treasured the fleeting victory of that explosive outburst from Buckley, which conversely haunted the conservative warrior until his death in 2008.

A death, incidentally, that Best of Enemies suggests Vidal—who died four years after Buckley—delighted in, if only because it gave Vidal the last word.