Mickey Kaus wrote a piece on Robert McNamara after the former Secretary of Defense's book, In Retrospect, came out in 1995:

McNamara's book confirms what he had often hinted: that he came to believe the war was unwinnable as early as 1965. At that point, as Paul Hendrickson of The Washington Post has noted, 1,335 Americans had been killed. Why didn't McNamara quit and speak out? He claims that would have been "a violation of my oath to uphold the Constitution." Cabinet officials who quit must do it "silently," he says, citing as a model Dean Acheson, who resigned from FDR's administration when he "found himself unable to accept the president's monetary policy."

Monetary policy! By the time McNamara left the Pentagon for the World Bank, another 14,000 Americans were dead. And of course the war didn't stop then. President Nixon continued it for five more years, although McNamara now says Nixon should have withdrawn. Surely whatever strictures prevented McNamara from criticizing Johnson wouldn't have prevented him from speaking out against Nixon. Even if he hadn't yet decided on withdrawal, simply giving voice to his doubts would have had an impact. Yet he didn't do it, while another 42,000 died. As McNamara puts it, defending his infamous quantitative approach to military success, "things you can count, you ought to count. Loss of life is one...."

And why, suddenly, having maintained his costly silence for so long, does McNamara break it now? Because, he says, he has "grown sick at heart witnessing the cynicism and even contempt with which so many people view our political institutions and leaders." Please. Wouldn't the cynicism have been less if he'd spoken up earlier, maybe even at the risk of losing his prestigious World Bank job? Let me offer an alternative--more cynical--explanation for McNamara's strange sense of timing, one that fairly leaps off the pages of his book: he is acting now to protect his posthumous reputation.

It's worth reading the full article.