One of the most important moments in Edward Kennedy’s life was a speech in October 1991 when, for the first time, he acknowledged his dark side, the inner demons that had destroyed his chances of becoming president.

“I realise that I alone am responsible for them, and I am the one who must confront them,” he declared.

Few figures in American history have waged such a long moral crusade in public while leading a private life that was often scandalous — a tale of heavy drinking and womanising, marked above all by an event that cast a shadow over Kennedy for decades: the Chappaquiddick car accident.

By the time of that fateful night on Martha’s Vineyard in 1969, Kennedy was forging a brilliant Senate career, but was already displaying the private flaws that were trademarks of the men in the Kennedy clan.

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By 1968 he had already lost all three of his brothers: Joseph, who was killed in the Second World War, and Jack and Bobby, both assassinated. He took Bobby’s death particularly badly. “I have never, ever, nor do I expect ever, to see a face more in grief,” said Frank Mankiewicz, one of his aides.

By the mid-1960s his marriage to Joan Kennedy was in trouble, because of his adultery and her growing alcoholism. Yet after Bobby’s death, and Richard Nixon’s presidential victory in November 1968, Kennedy found himself the unofficial front-runner for the 1972 Democratic nomination.

Then came Chappaquiddick. On the night of July 18, 1969, Kennedy had attended a party on Chappaquiddick Island for the “Boiler Room Girls”, a group of young aides who had worked on Bobby Kennedy’s presidential campaign. Kennedy left the party with one of them, Mary Jo Kopechne, who was 28.

He drove the Oldsmobile Delmont 88 in which they they were travelling off Dike Bridge and into Poucha Pond inlet. Kennedy escaped from the overturned vehicle and swam to safety but Kopechne drowned. He did not report the accident until her body was discovered the next day.

On July 25, 1969, Kennedy pleaded guilty to leaving the scene of an accident and was given a two-month suspended sentence. He always claimed that he was not drunk, nor that there was any romantic link between him and Kopechne, but the incident generated conspiracy theories for years.

It also destroyed any hopes that Kennedy might have had to run for president in 1972. While he was mulling over a 1976 run, the Chappaquiddick scandal was still in the news, with several leading US media outlets reassessing the events of the night and questioning Kennedy’s version of events.

His wife, Joan, who had been treated for alcoholism in several clinics over the years, separated from Kennedy in 1977 and the couple divorced in January 1981.

Kennedy challenged Jimmy Carter, the incumbent President, for the 1980 Democratic nomination, but again Chappaquiddick was a bigger factor than he and his staff had predicted. During a St Patrick’s Day parade in Illinois in March 1980, Kennedy wore a bullet-proof vest as hecklers yelled: “Where’s Mary Jo?”

In the 11 years that followed his divorce, Kennedy’s private life descended into sometimes vaudevillian excess. During the 1980s his weight fluctuated wildly and his face grew more florid and blotchy. He often drank and caroused in Washington with Chris Dodd, a fellow senator, and chased women. In 1986 his son Patrick entered rehab, followed by his brother Ted Jr in 1991.

In 1989 European paparazzi photographed Kennedy having sex on a motorboat, prompting the Alabama senator Howell Heflin to quip that he was glad to see Kennedy had “changed his position on offshore drilling”. In 1990 a portrait appeared in GQ magazine entitled “Ted Kennedy on the Rocks”.

Then came the rape trial of his nephew William Kennedy Smith — the most watched televised court case until that of O. J. Simpson. On Easter weekend in 1991 Kennedy organised a weekend party at the family’s Florida estate. Late one night he asked his son Patrick and nephew William Kennedy Smith to accompany him to a bar.

They left with two women: Patricia Bowman, 29, a single mother, and Michelle Cassone, a waitress. Ms Cassone said that she and Patrick were “cuddling” in a bedroom when Edward Kennedy entered in just a nightshirt, a development that made her leave. Mr Kennedy Smith and Ms Bowman ended up on a beach. He said that they had consensual sex. She accused him of rape but he was acquitted.

The scandal caused a media firestorm in which Edward Kennedy, as Time magazine wrote, was depicted as “a Palm Beach boozer, lout and tabloid grotesque”.

Then, in 1991, he found his redemption in Vicki Anne Reggie. They were married a year after meeting. At last, Kennedy had found someone strong enough to stabilise his personal life.

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