To the recent spate of 50th-anniversary reflections on key political and cultural milestones – the 1963 March on Washington, the assassination of John F. Kennedy, the Beatles’ appearance on the Ed Sullivan Show – here’s one to add: The presidential campaign of Barry Goldwater, the most influential also-ran in modern American politics.

Goldwater was nicknamed “Mr. Conservative,” but now even liberals adore him. Robert F. Kennedy Jr. penned an essay a few years back effusive in its praise for Goldwater, whom he described as an exemplar of civility, decency, and integrity. Goldwater was “neither mean-spirited nor racist,” wrote Kennedy; he challenged the liberals of his time through “sensible argument and honest conviction.” A 2006 documentary produced by CC Goldwater, Barry’s liberal’s granddaughter, is strewn with such liberal tributes; Hillary Clinton, James Carville, and Walter Cronkite are among those who attest to the man’s statesmanship and charm.

How things have changed.

In 1964, Goldwater appalled the political establishment. Though the blunt-spoken Arizonan’s bestseller, “The Conscience of a Conservative,” had made him a hero on the right even before his White House run, liberal commentators seemed shocked to discover that his conservatism was for real. When he declared, in his acceptance speech at the Republican convention in San Francisco, that “extremism in the defense of liberty is no vice, and … moderation in the pursuit of justice is no virtue,” they were aghast.

What followed was one of the most ruthless campaigns of invective in US political history. Goldwater and his conservative supporters were repeatedly likened to Nazis, madmen, and warmongers. Jackie Robinson said he knew “how it felt to be a Jew in Hitler’s Germany.” Lyndon Johnson’s notorious “daisy” commercial showed a little girl picking flower petals, until she is overwhelmed by the mushroom cloud of a nuclear explosion. A month before the election, the cover of Fact magazine blared: “1,189 Psychiatrists Say Goldwater is Unfit to be President!”

Conventional wisdom said Goldwater didn’t have a prayer, and conventional wisdom was right. On Election Day, the Republican ticket suffered a crushing defeat. Johnson amassed 61 percent of the popular vote, the highest percentage in presidential campaign history; Democrats at every level swept to lopsided majorities reminiscent of the FDR landslide of 1936. Goldwater – the most ideologically conservative GOP nominee since Calvin Coolidge – hadn’t just lost, he’d been buried.

What that meant, said the nation’s most respected political analysts, was obvious: Conservatism was political poison, and the GOP had just swallowed a near-fatal dose.

“Barry Goldwater not only lost the presidential election yesterday, but the conservative cause as well,” pronounced James Reston of The New York Times. “He has wrecked his party for a long time to come.” Time magazine said Republican conservatives had been so completely humiliated “that they will not have another shot at party domination for some time to come.”

But about that, conventional wisdom was dead wrong. So were the Eastern liberal Republicans who had long dominated the GOP. They didn’t seek to roll back the vast increase in government programs that Democrats since the New Deal had embraced; their pitch to voters was that they could manage those programs with more businesslike efficiency. Many establishment Republicans were as turned off by Goldwater’s ardent conservatism as Democrats and media liberals were. The chairman of the New York Republican Party called the Election Day debacle the “shattering price” the GOP had paid for its “erratic deviation from our soundly moderate 20th-century course.” The voters had spoken, and conservatism had been “decisively vetoed.”

Hardly.

Conservatism was no suicide pill, it was the Republican future. “In your heart, you know he’s right” had been a much-mocked Goldwater campaign slogan (“In your guts, you know he’s nuts” was one rejoinder), but it became increasingly clear that the heart of the Republican Party did indeed incline rightward. Goldwater may not have been a very good presidential candidate, but millions of Americans found his conservative ideals refreshing and inspiring.

Even as Goldwater was losing 44 states, there were remarkable signs of grassroots enthusiasm for his political message. Historian Steven Hayward points out that the Goldwater campaign received more than 1 million contributions, 400,000 of them in amounts under $10. Four years earlier, Richard Nixon’s campaign had received only 40,000 contributions.

In 1964, the GOP’s center of gravity began its decisive shift to the West and South. Of the 12 presidential elections that followed 1964, Republicans have won seven, and every GOP ticket since the Goldwater campaign has included a conservative. Who doubts today that conservatives constitute the party’s base? Until 50 years ago, Republican presidential hopefuls competed for the imprimatur of the party’s liberal establishment. Now, even the Republican establishment calls itself conservative – while Goldwater, savaged by Democrats in 1964, is described with affection and admiration by Democrats in 2014.

Goldwater lost a presidential election, but he changed the face of American politics. All winning candidates appeal to the mainstream. But only the most influential redirect it.

(Jeff Jacoby is a columnist for The Boston Globe).