But in two days of secret grand-jury testimony June 23 and 24, 1975, he shed no light on how the key portion of the secretly recorded conversation between Nixon and Chief of Staff H.R. "Bob" Haldeman shortly after the Watergate break-in arrests got erased.
"I practically blew my stack" after learning of a gap in the recording subpoenaed by Watergate prosecutors, and ordered his staff to "find out how this damn thing happened," he said under oath in testimony released by the Nixon Presidential Library and Museum in Yorba Linda, Calif., Thursday in response to an judge's order.
Asked about the erasure, Nixon -- who resigned Aug. 9, 1974, facing near-certain impeachment in the House and a strong possibility of a conviction in the Senate -- said he didn't know how it happened.
"If you are interested in my view of what happened, it is very simple. It is that it was an accident," he said.
Nixon's personal secretary, Rose Mary Woods, said Sept. 29, 1973, she was reviewing the June 20, 1972, tapes -- three days after the Watergate break-in -- when she accidentally erased part of a recording by pushing the wrong foot pedal on her tape player when answering the phone.
She demonstrated to news photographers how this could have happened.
Forensic analysis by the National Archives concluded in 2003 the gap in the tape -- one of the great mysteries of the Watergate scandal -- was caused by at least five separate erasures and perhaps as many as nine, The New York Times reported at the time.
Nixon -- who had been pardoned by successor President Gerald Ford by the time he testified and therefore had immunity from prosecution for any crimes he may have committed -- lectured prosecutors they were adopting a "double standard" by looking only at the actions of his administration, saying Democratic administrations had done much the same.
Vilifying him "is going to make you much more popular with the Washington press corps, with the Georgetown social set, if you ever go to Georgetown, with the power elite in this country," he said.
"But, on the other hand, think of your children -- they are going to judge you in the pages of history," Nixon told prosecutors.
In a long discussion about the sale of ambassadorships, Nixon was adamant there was no quid pro quo with campaign donors.
For ambassadors to key allies such as Britain or France, "the most important thing to me was that he had to be qualified," Nixon testified. But for less-strategic nations such as Luxembourg or El Salvador, he followed the traditional U.S. practice of naming rich donors to the posts, a report on the testimony by the Center for Public Integrity indicated he said.
"Some of the finest ambassadors ... have been non-career ambassadors who have made substantial contributions," he said, adding he never made "an absolute commitment" of an ambassador post to anyone in return for a six-figure contribution.
Business leaders and other amateur statesmen were actually often more effective than State Department professionals because they could be trusted, Nixon said.
"As far as career ambassadors, most of them are a bunch of eunuchs," he said. "They aren't for the American free-enterprise system."
Earlier administrations also gave ambassadorships to contributors, he said, recalling President Franklin D. Roosevelt's appointment of Joseph P. Kennedy as ambassador to Britain from 1938 until late 1940, when Kennedy resigned under pressure for suggesting during World War II's Battle of Britain that democracy was "finished in England" and might also be in the United States.
Kennedy was a "pretty good appointment," Nixon said. "After all, at least he increased the Scotch supply."