On Nov. 15, 1969, a million peo ple, give or take a few hundred thousand, marched on Washington to protest the war in Vietnam. It was my first major demonstration. You never forget your first.

In Washington, D.C., when the sun came up the air was cystal clear and far colder than this Massachusetts native was prepared for. Before entering Georgetown University two months before, I’d been out of New England exactly three times in my life, once to Virginia, twice to D.C., but never in November. Wasn’t Washington a southern city? I didn’t expect to need winter clothes until after Thanksgiving break. Which is why I was out on Pennsylvania ave., N.W., between 6th and 7th streets, shivering in the warmest coat I had with me, which wasn’t a coat at all but a gendarme-like cape in navy blue wool, with nary a pocket to stuff my ungloved hands in.

I was a marshall. Within a few years the term of choice would become peacekeeper, but the job was pretty much the same: to form a buffer zone between the demonstrators and the cops, and to defuse any tensions on “our side” before they escalated into trouble with “their side.” That morning there were no tensions on my block. We made regular coffee runs to the nearest deli; I wasn’t a coffee drinker in those days, but Styrofoam coffee cups made dandy handwarmers and whatever warmth went down my gullet was bound to radiate outward. Marshalls brought cups for cops (who were better dressed for the temperature than many of us). The guy next to me and I quickly established that we both knew most of Tom Lehrer’s repertoire, so we ran through a good portion of it, drawing in several more singers and amusing our nearer comrades, including (I’m sure) some of the police.

Rumors flew up and down the line about how many people were mustered at the Capitol, waiting to start the march, how many buses were arriving from how far away. For the past two days I’d been helping with housing and feeding out-of-town demonstrators at my college; rumor control was part of the job. I’d never suspected just how fast and far bogus information can spread. So while I didn’t believe most of the wild estimates, I fervently hoped that the highest were the truest.

Then the first marchers appeared down the long, broad stretch of Pennsylvania Avenue. Words still fail me; the clichés get there first. Mouth open, heart in throat — my first peak spiritual experience, being lifted beyond words into a transcendent union with a power greater than I’d ever glimpsed before.

The march went on for hours. An unending torrent of people, coming and coming, ever changing: different signs, different flags, different chants, flowing on and on and on, colorful, jubilant. E pluribus unum; out of many, one . . .

In the years since I’ve heard plenty of people say that the demonstrations stopped the war and performed other miracles. Every major demonstration comes with stories about how the sitting president was at Camp David or out of the country or otherwise paying no attention whatsoever to that highly visible and audible though undeniably tiny minority of the U.S. population marching in the streets: the high officials pretend they’re above all that, they couldn’t possibly be swayed by such riffraff. (If you want to sway those officials, $500,000 speaks louder than 500,000 citizens.) Did the demonstrations stop the war? Who knows.

In the end, does it really matter? Great demonstrations change you forever, expand your vision of the world and your place in it, and ultimately your sense of your own power. What would I be, where would I be, who would I be, if I hadn’t been standing on Pennsylvania avenue, N.W., on Nov. 15, 1969, between 6th and 7th streets? Something else, somewhere else, someone else, most likely.

Susanna Sturgis lives in West Tisbury.