More irony: Nixon retained a sizable following in the African-American community, which had historic ties to Republicans dating from the age of Abraham Lincoln and which remembered Nixon’s support for voting rights legislation. Nixon won 18 percent of the black vote in 1972, a figure no Republican White House candidate has reached since.

He won a 49-state landslide that year, the great divider winning a nearly unprecedented majority, yet he would never be able to unite the nation.

The 1972 break-in at the Democratic Party’s Watergate headquarters triggered the unspooling of intricate, sometimes amateurish, sometimes criminal plots to embarrass and defang enemies. Little by little, the revelations poured out during 1973 and 1974: enemies lists, break-ins, misuse of government agencies, cover-ups.

Nixon admitted no wrongdoing in his Aug. 8, 1974, resignation speech. When Gerald Ford took office the next day, he solemnly declared, “Our long national nightmare is over.”

Nixon’s role in that nightmare remains the nation’s most vivid memory of him ever since. “You can’t cover the Watergate blemish with makeup,” said veteran political analyst Stuart Rothenberg.

In Washington, the newly emboldened Congress, having helped bring down a president, became more assertive, making the Washington process somewhat messier but also somewhat more transparent. Jimmy Carter struggled to win approval of a comprehensive energy program; Ronald Reagan had to rely on Democrats to win approval of his signature tax cut plan in 1981.

Nixon died in 1994. Seven presidents have served in the office since he resigned. History is starting to give Nixon a fresh, more dispassionate look, and Wednesday night, his loyalists will try to give the experts a push.

They’ll offer reminders like that of Robert Bostock, a former Nixon aide and co-curator of the centennial exhibit at the Nixon Presidential Library & Museum.

“His greatest legacy is that he left the world a safer and more peaceful place, and he appreciated the difference government could make in the lives of average Americans,” Bostock said. “He knew how to get things done.”