Where were you in the 1960s? And what were you? A toddler, a grade schooler, a teenager? A young adult? Were you already old enough to form your own memories? Or were you old enough but in the “if you can remember The Sixties you really weren’t there” category?

Of course, if you’re like most people, you were nowhere. You hadn’t been born yet. You didn’t exist. But wherever and whatever you were or weren’t, it’s a safe bet that you’ve heard about The Sixties – quite enough, maybe. Ad nauseam, maybe.

Or maybe not.

Technically, the sixties began on 1 January 1960 and ended on 31 December 1969. But The Sixties are another story. The Sixties are too protean to be hemmed in by calendrical niceties. The sixties may be just another decade, but The Sixties are something more – a mood, a state of mind, a way of life, a congeries of sounds and images. The Sixties contain multitudes.

There is a continuing theological controversy among sixtiesologists concerning when The Sixties can properly be said to have begun and ended. Tuesday 8 November1960 – the day Senator John F Kennedy was elected president – has a pretty good claim to the beginning. Kennedy’s campaign slogan, which appeared on every campaign poster, had been LEADERSHIP FOR THE 60’s. Out with the dull, conformist, priggish, crewcut, Eisenhowerish Fifties! In with the dashing, exciting, daring, sexy, slightly longer-haired, Kennedyesque Sixties!

A darker view – the view I take – sets the clock of The Sixties ticking three years later. The assassination of President Kennedy was a crack in time. Like Sunday 7 December 1941; and like Tuesday 11 September 2001; Friday 22 November 1963 was “a date that will live in infamy”. And, like them, it was a day that is remembered in vivid detail by those who experienced it.

I was taking a noontime shower in my Harvard dorm room, having been as usual up till dawn getting out the college daily, the Crimson. I heard a faint, muffled radio news bulletin coming through the wall from the neighboring room. As I dried off, I turned on my own radio. I can still see the edge of the shower stall and the little bathroom window next to it. On the grass below, a girl was standing under a tree, weeping. The Crimson put out an extra that afternoon, but without my help. It felt too much like a schoolboy stunt. Rightly or wrongly, I didn’t want to play newspaperman. I didn’t want to be distracted from the communal grief all around me.

So The Sixties, in this conceit, began either in 1960 or, like Philip Larkin’s sexual intercourse, in 1963. And the ending? That too has long been a subject of debate. There are plenty of nominees, two of which may be considered the frontrunners. Like the beginnings, one is light and one is dark. The light one: Friday 9 August 1974, the day Richard Nixon resigned the presidency, freeing the nation from a quarter-century of having had him to kick around. The dark one: Altamont. Sunday 6 December 1969. Google it. Or see the movie.

Whenever The Sixties started and ended, it is universally recognized that 1968 was the peak year – the climactic year, a singular year, a year of events and sensations that cascaded with an intensity that was sometimes unbearable, sometimes ecstatic. In a modest way, 1968 was the kind of year that pushes history in some unforeseen, astonishing direction – a gentler little brother to 1492, 1776, 1848, 1914, 1945, and 2001.

It is possible to build a narrative around two currents of the year’s events, currents that melded and crisscrossed and fed off each other, to startling effect: the music, mostly a kaleidoscopic, wildly imaginative explosion of rock’n’roll; and the politics, mostly a politics of protest – protest against the Vietnam war, against racial injustice, and, more broadly, against what was experienced as the joyless, stultifying blandness of mainstream American life.

Those two currents, the music and the protests, washed over me as they did over millions of others. In 1966, a year out of college and a newly minted cub reporter for Newsweek, I was lucky enough to land in San Francisco. Something was happening there, and I found myself in a position to absorb it.

The scene, cultural and political, was quite something. A new kind of music – rooted in blues, rock, and electronica, and supercharged by psychedelia – was drawing motley-dressed weekend crowds to a couple of repurposed old dance halls, the Fillmore Auditorium and the Avalon Ballroom. For $2.50 you could spend hours listening and dancing to bands that were still unknown back east or down south in LA – bands still without record contracts but with wonderful names: Jefferson Airplane, the Grateful Dead, Big Brother and the Holding Company, Quicksilver Messenger Service – often paired with iconic bluesmen like Muddy Waters and James Cotton. The walls were mesmerizingly alive with rhythmically pulsating, ever-changing liquid projections. It was, in the patois of the moment, mind-blowing. For the gentle dreamers that Herb Caen, the San Francisco Chronicle’s gossip columnist, had dubbed hippies, the Fillmore and the Avalon were Carnegie Hall and the Philharmonic.

If San Francisco was the cultural capital of a new youth commonwealth, Berkeley was the political capital. The campus of the University of California was the staging area for demonstration after demonstration. Further left, would-be revolutionaries flirted with violence. The anger that in 1968 would explode in the streets of Chicago was growing apace. So was the reaction. A onetime movie star, Ronald Reagan, ran for governor and won, largely on a promise to bring all those spoiled, unpatriotic campus brats to heel.

Like every young man of my generation, I had to reckon with the draft. I was against the war, of course, but I didn’t think I had the stomach to go to jail over it. I had zero desire to go to any more schools, graduate or otherwise. I was unmarried and childless. Canada was not my country, my country was the United States of America. I wasn’t physically or mentally ill and was too proud to fake it. And I wasn’t a conscientious objector. On the other hand, I didn’t want to get killed either. My solution was the US navy.

I got a haircut and reported to the naval base at Newport, Rhode Island, for three months of officer training. From there I asked to be sent to Vietnam, but it wasn’t like it sounds. Unless you were a flier (like John McCain, the future senator), a Seal (like Bob Kerrey, also a future senator) or a member of the Riverine Force (like John Kerry, a future senator, presidential nominee, and secretary of state), being a naval officer in Vietnam, especially a “public affairs” officer like me, posed very little physical risk. Instead, however, the navy, in its wisdom, assigned me to a desk job in lower Manhattan.

I stole away from the office whenever I could, and devoted the time to salving my conscience. I pitched in at the ramshackle headquarters of the War Resisters League. In March, after Robert Kennedy entered the presidential race, I took to hanging around his Manhattan headquarters, doing layouts and writing headlines for the Kennedy Current, the campaign’s weekly tabloid.

As the year rushed on, the pace of events grew ever more frenzied: the bloody shock of the Tet Offensive; the electoral abdication of President Lyndon Johnson; the assassination of Martin Luther King Jr and the riots that followed; the murder of Robert Kennedy; the chaotic, riotous Democratic convention in Chicago; Nixon’s hairsbreadth victory over Hubert Humphrey in November. And me? Well, at Christmastime I got the orders to Vietnam (as a “recreation officer” at the US base in Da Nang) I’d hoped for two years earlier. Only this time I didn’t want to go. My antiwar sentiments had hardened to the point that I decided I preferred jail to further military service, and I announced my intention to refuse the orders.

But before I could achieve fame as a martyr for peace an unexpected medical difficulty developed: I had a wisdom tooth pulled, the wound bled for days, and when I was diagnosed with a (relatively mild) form of hemophilia, the navy quickly mustered me out. I had managed to have it both ways: veteran (kind of) and resister (in a way).

And what about the current president of the United States? Where was he in ’68? Why safe and sound in Philadelphia, where, that June, the young Donald Trump completed his studies at the Wharton School of Business. Tragically, he was unable to serve in what he now calls “our great military”. He scored a total of five draft deferments: four on account of student status followed by a medical disqualification for a symptomless case of “bone spurs” in the heel of one foot. Which foot? He can’t remember.

Why didn’t I think of that?

In 1968 the sixties were almost over, but The Sixties have never fully gone away. For me, and no doubt for many others of my vintage, it’s hard to believe that half a century now separates us from that momentous, tumultuous year, and that 1968 is now as distant in time as 1918 – the year of the end of World War I, the consolidation of Bolshevik power in Russia, and the flu pandemic that killed 50 million people – was in 1968. Fifty years from now, it’ll be 2068.

The Sixties again! I can’t wait!

• This is an extract from the introduction to the 30th-anniversary edition of 1968 in America: Music, Politics, Chaos, Counterculture, and the Shaping of a Generation by Charles Kaiser, published in the US by Grove Press on 17 April