This month is the 40th anniversary of the fractious Democratic National Convention that nominated South Dakota Sen. George McGovern as his party’s presidential candidate.

In the November 1972 election, he suffered an overwhelming defeat, widely interpreted as the rejection of liberalism.

Just eight years earlier, Republican Sen. Barry Goldwater had been soundly defeated in an election that, at the time, was similarly interpreted as a rejection of conservatism.

History has shown that the verdict on Goldwater was wrong, and I believe that the same can be said about the McGovern campaign and defeat.

I was McGovern’s Senate executive assistant and his “body man,” traveling around the country with him almost continuously during the campaign. In that role, I understood McGovern’s key beliefs and saw his supporters up close.

The principal focus of both the candidate and his supporters was not a liberal agenda. It was opposition to America’s role in the Vietnam conflict and the desire to end American involvement immediately.

McGovern drew avid support from Hollywood actors and NFL players, leading economists and progressive politicians, mainly because of his leadership in opposing the Vietnam War. While they might agree with some of his proposals on taxation or welfare, all issues were secondary to opposition to the war.

During the campaign, I worked closely with some of the top academic economists in the United States. I was always convinced that they contributed their advice to help McGovern mainly because of their opposition to the Vietnam War. Their proposals, most of which McGovern espoused, were hardly radical.

Those of us in the McGovern campaign thought he had a chance of winning against an incumbent president, because he was right about Vietnam. We believed that a majority of Americans would see the issue as we did, as a huge mistake that undermined the very foundations of the country, overriding all other issues. People would vote against the war by voting for McGovern.

McGovern had tried to get the Senate to vote in favor of cutting off funding for the war. His proposal, made with Republican Sen. Mark Hatfield of Oregon, was called “the Amendment to End the War.” When the Senate acted in 1970, it rejected the proposal, with only 39 of the 100 senators voting for it.

In effect, the McGovern candidacy was an appeal to the public to overrule that vote. As president, he could bring American involvement in Vietnam to an end by vetoing appropriations for it.

When the votes were counted after the 1972 election, McGovern received 37.5 percent, remarkably close to the Senate result. It turned out that the Senate had reflected public opinion; a majority of the public did not share our views about Vietnam.

So convinced had we been of the obvious merit of our view that we had incorrectly assumed that others either shared it or would come to that view. In an often-repeated quote, Pauline Kael, the film critic for the New Yorker magazine spoke for some of us, saying, “I live in a rather special world. I only know one person who voted for Nixon.”

While some Democratic voters rejected McGovern on grounds other than the war, some Republicans voted for him because of their opposition to the war. Newly enfranchised young people did not break as strongly for him as we had hoped, and he could not overcome the political strength of an incumbent president.

McGovern should not be tied together with Goldwater in a misguided effort to show that Americans rejected either extreme.

It is true that the campaign of President Richard Nixon used McGovern’s supposed liberalism on some issues other than the war as part of the effort to defeat him. He was falsely charged with supporting “amnesty, abortion, and acid.” In fact, he supported amnesty for Vietnam draft resisters, but not deserters, favored leaving abortion to the states and did not favor legalization of drugs.

It is also true that McGovern, who quickly understood the significance of the Watergate break-in, tried to make it a campaign issue. But by the time that story of the Nixon campaign’s burglary of the Democratic National Committee became known, the voters had made up their minds.

Polling after the election, when the facts about Nixon’s involvement in the Watergate cover-up became known, showed that people claimed to have supported McGovern far in excess of the votes for him.

Looking back at 1972, especially in light of today’s ideological divide, it may be helpful to understand that it was a referendum on Vietnam more than a verdict on liberalism.