Carl Bernstein and Bob Woodward are the co-authors of two Watergate books, “All the President’s Men,” published in 1974, and “The Final Days,” published in 1976. This is their first joint byline in 36 years.

As Sen. Sam Ervin completed his 20-year Senate career in 1974 and issued his final report as chairman of the Senate Watergate committee, he posed the question: “What was Watergate?”

Countless answers have been offered in the 40 years since June 17, 1972, when a team of burglars wearing business suits and rubber gloves was arrested at 2:30 a.m. at the headquarters of the Democratic Party in the Watergate office building in Washington. Four days afterward, the Nixon White House offered its answer: “Certain elements may try to stretch this beyond what it was,” press secretary Ronald Ziegler scoffed, dismissing the incident as a “third-rate burglary.”

History proved that it was anything but. Two years later, Richard Nixon would become the first and only U.S. president to resign, his role in the criminal conspiracy to obstruct justice — the Watergate coverup — definitively established....

In the course of his five-and-a-half-year presidency, beginning in 1969, Nixon launched and managed five successive and overlapping wars — against the anti-Vietnam War movement, the news media, the Democrats, the justice system and, finally, against history itself. All reflected a mind-set and a pattern of behavior that were uniquely and pervasively Nixon’s: a willingness to disregard the law for political advantage, and a quest for dirt and secrets about his opponents as an organizing principle of his presidency.

Long before the Watergate break-in, gumshoeing, burglary, wiretapping and political sabotage had become a way of life in the Nixon White House....