Decorated military general, 60, to offer his 'deep regret' for affair with biographer that led to his resignation as CIA director

David Petraeus, one of America's most decorated generals, is expected to make his public comeback Tuesday night with an apology for the extramarital affair that led to his resignation.

Petraeus is to quaintly refer to the affair as "slipping his moorings" during a speech at the University of Southern California.

Petraeus resigned as CIA director in November after the affair was discovered during an FBI investigation into a potential breach of security that involved email exchanges.

At the time, his stock was so high that he was being mentioned as a potential Republican presidential candidate.

In an advance of the speech obtained by the New York Times, Petraeus is expected to say: "Needless to say, I join you keenly aware that I am regarded in a different light now than I was a year ago. I am also keenly aware that the reason for my recent journey was my own doing.

"So please allow me to begin my remarks this evening by reiterating how deeply I regret — and apologise for — the circumstances that led me to resign from the CIA and caused such pain for my family, friends and supporters."

Such a show of contrition is part of a pattern in US, the first stage in a process that almost always allows high-profile figures to return to public life.

Since his resignation, Petraeus has laid low, staying mainly at home, apart from his daily regime of long runs or bike runs. But he has recently been seen around Washington at lunches and thinktanks. After his departure from the CIA, there were flattering opinion pieces in the media expressing support for him, saying he was too gifted to be left on the sidelines.

A counter-view was presented earlier this month in a Guardian report about US advisers and secret detention and torture centres in Iraq and linked Petraeus for the first time to abuse.

There is no indication yet what role Petraeus, 60, has in mind for himself, whether in business, politics, helping veterans or some other field. Until he resigned from the military in 2011 to take up the CIA job, Petraeus gave speeches around Washington that bordered on the political, leading to speculation that he envisaged a late career in politics.

On November 9, he issued a statement announcing his resignation and said he had made an error of judgment. He had had an affair with his biographer, Paula Broadwell, who wrote a largely uncritical account of his life titled All In.

His wife of 37 years, Holly, whom he met while a student at West Point military academy, has stayed with him.

In his speech Tuesday, Petraeus is set to say: "I know that I can never fully assuage the pain that I inflicted on those closest to me and on a number of others. I can, however, try to move forward in a manner that is consistent with the values to which I subscribed before slipping my moorings and, as best as possible, to make amends to those I have hurt and let down."

According to the advance, he will say: "Life doesn't stop with such a mistake; it can and must go on."

Petraeus is the keynote speaker at a dinner for about 600 connected with the university's reserve officers' training corps and veterans.

The USC president CL Max Nikias, on the university website, offers a flattering biography of Petraeus. "In our post 9/11 world, General Petraeus' influence on our military is unmatched, and his contributions to the CIA are far-reaching. General Petraeus completely reshaped American military tactics and promoted our nation's counterinsurgency strategy.

"Petraeus is arguably the most effective military commander since Eisenhower."

The invitation to speak at the dinner had been issued before his resignation.

In the speech, Petraeus is to refer to the problems facing troops making the transition to civilian life.

"There is often a view that, because an individual was a great soldier, he or she will naturally do well in and transition effortlessly to the civilian world," he is set to say, in words that may be addressed to his own life as well as other veterans.

"In reality, the transition from military service to civilian pursuits often is quite challenging."

© Guardian News and Media 2013