In a book-lined living room in Longmeadow, John Fitzgerald — a retired high-school history teacher — leafed through a stack of papers from his trip to Chicago in 1968, as a Massachusetts delegate to the Democratic National Convention.

“This was something I wrote up back then — ‘Journal of a Delegate,’” Fitgerald said, and began reading aloud. “Thursday, left Bradley [Airport] 8 a.m., arrived Chicago 9:30 a.m. Polluted air over Chicago. Very hot and humid. ... Stifling monoxide stench.”

That sickly atmosphere fit the nation’s mood. The country was still reeling from the recent assassinations of Robert Kennedy and Martin Luther King Jr., while in Vietnam, more than 1,000 Americans were dying every month.

Fitzgerald was a Vietnam vet — a Purple Heart and Bronze Star recipient who’d decided the war was wrong.

“If they asked me, what do you really want to see us do, I would’ve said, I want to see you take all the troops out of there tomorrow,” Fitzgerald recalled.

Hence, his desire to nominate Minnesota Senator Eugene McCarthy, whose anti-war campaign had prompted President Lyndon Johnson’s stunning decision not to seek re-election.

Also traveling to Chicago that August was Michael Kazin, who is now a history professor at Georgetown. Back then, he was a Harvard undergrad and member of the radical group Students for a Democratic Society, or SDS.

“I wanted to disrupt the convention, to be quite honest with you,” Kazin said. “The Democratic Party was the party that had prosecuted the war, that escalated the war. And even though I’d worked as a 16-year-old to elect Lyndon Johnson in 1964, by 1968 I was completely done with the Democratic Party.”

Meanwhile, the party itself was on the verge of cracking up. The delegates in Chicago ran an untenable ideological gamut, from old-school Southern segregationists to people who, today, would be labeled “progressive.” Fitzgerald was in the latter group: In addition to an anti-war nominee and an anti-war platform, he wanted the convention to seat racially integrated delegations from the south.

“Alabama, Georgia, they had all white delegations, and were opposed to the Civil Rights movement, and in some cases openly supportive of [George] Wallace,” Fitzgerald said, referring to the ardent segregationist who was making a third-party presidential run.

“[Vice president] Hubert Humphrey and Johnson were counting on those people voting for them,” he added, alluding to the fact that Humphrey was campaigning as Johnson’s ally and heir. “So one of the challenges we had was to stop the pro-Humphrey delegates and elect the challenge delegates [who] were sympathetic to the McCarthy antiwar movement.”

The challenge for Kazin and his fellow SDS members was different. Instead of turning the Democrats against the Vietnam war, they wanted to turn the antiwar movement against the Democrats.

“We had a campaign to go to Chicago and try to convince young antiwar activists who were supporting Eugene McCarthy at the time, and those who had been supporting Robert Kennedy before he was assassinated, to give up on the Democrats and come over to our side, and be involved in a real radical movement,” Kazin said.

One which, among other things, embraced violence as a tactic.

“Some of us went on a sort of mini-riot through the Loop, through downtown Chicago, I think that Saturday night, before the convention began,” Kazin said. “Some people smashed windows, some people smashed — I wasn’t one of them, but some people smashed windows in police cars. ... You really [felt] like you’d struck a blow against the American empire, which of course in retrospect was quite ridiculous.”

Inside the convention hall, things felt equally unhinged. In one infamous episode, a young Dan Rather was pushed to the ground as he tried to interview a delegate being escorted out by security, his cries broadcast live to a national audience: “Don’t push me! Take your hands off me unless you intend to arrest me!”

On August 28, the chaos outside and inside the convention converged. Chicago police cracked down hard on 10,000 protesters, swinging billy clubs and spraying tear gas in what was dubbed the Battle of Michigan Avenue and later described, in an outside report, as a police riot.

Meanwhile, on the convention floor, Connecticut Senator Abraham Ribicoff decried that violence as he nominated South Dakota Senator George McGovern, who also opposed the Vietnam war. “With George McGovern as president of the United States, we wouldn’t have to have Gestapo tactics on the streets of Chicago,” Ribicoff said.

That enraged Chicago Mayor Richard Daley, who shouted back an unprintable response. But ultimately, Ribicoff’s pitch failed. The next day, the Democrats nominated the pro-war Humphrey, even though he hadn’t run in any primaries and the majority of the party’s primary voters had backed anti-war candidates.

“The way the McCarthy campaign ended, in the perception of a lot of young people in America in particular, electoral politics was fixed,” Fitzgerald said. “It was broken. So a lot of people walked away from ’68 with a bad feeling about whether they should ever participate in electoral politics again. That still exists.”

As Fitzgerald sees it, the most recent Democratic contest shows the party still hasn’t learned from history.

“They ignored the lesson of ’68,” he said. “They locked out Bernie Sanders and his supporters. That Democratic National Committee was locked into Hillary Clinton. [But] that wasn’t where the majority of Americans were.”

Michael Kazin’s regrets are different. He was arrested in Chicago, and says after his release, a group of police actually threatened to kill him and his friends.

Still, in hindsight, Kazin thinks he and other radicals pushed their provocation too far.

“To be fair — and at the time, I wasn’t being fair to the police — but they felt under siege, too,” Kazin said. “I mean, after all, people like me, we were talking about revolution. We were calling the police ‘pigs.’”

Kazin notes that a post-convention poll showed most Americans backed the police, not the protesters — and that Richard Nixon’s law-and-order message helped him win the presidency that fall.

“The war in Vietnam made a lot of people a little crazy,” Kazin said. “And I think it pushed the New Left, of which I was a part, to do some things which hurt our cause in the long run, which helped build a conservative movement.”

The divide created by the chaos of 1968 is still with us. While many Democrats see President Trump as a Nixon-esque figure plagued by scandal, many Republicans see a leader who stands with law enforcement, and against crime and illegal immigration. It happened five decades ago, but in the realm of politics, the 1968 Democratic Convention isn’t really history at all.