Watergate
Watergate was so much more than a single crime and cover-up that it is impossible to summarize the tangle of abuses of presidential power that today are grouped under the name of the hotel where the Democratic National Committee had its offices. The arrest of five men in those offices on June 17, 1972, was the first step toward unearthing a host of administration misdeeds. It was to hide those other crimes that Nixon and his men launched the cover-up, the investigation of which helped to unravel that string of illegal conduct.
Indeed, Watergate was far from the first break-in. A year earlier, Nixon had unconstitutionally created his own secret police organization, the Special Investigations Unit, to unearth a conspiracy that he feared would leak some of his most damaging foreign policy secrets, including the secret bombing of Cambodia and Laos. The President, however, could not convince FBI Director J. Edgar Hoover that such a conspiracy actually existed. Nixon also wanted to expose the alleged conspiracy in the press, something the Justice Department could not legally do. He decided he needed his own team to investigate the conspiracy and leak damaging stories about it. Thus was born the SIU, better known by its nickname, "The Plumbers," an inside joke about its mission to fix leaks.
The immediate cause of Nixon's concern was the publication of the Pentagon Papers, a massive study of the Vietnam War as it was conducted by Nixon's predecessors. The study was commissioned by Robert S. McNamara, the secretary of defense under Kennedy and Johnson. It did not contain a word about the Nixon administration but it did reference top secret documents from the two prior presidencies. The leak ignited Nixon's fear that his own politically damaging secrets would be exposed before the 1972 election. He suspected a conspiracy and resolved to destroy it before it destroyed him.
It was to find out more about this imaginary conspiracy that two of the Plumbers, ex-CIA agent E. Howard Hunt and ex-FBI agent G. Gordon Liddy, planned and carried out an operation to discredit Daniel Ellsberg, the man who leaked the Pentagon Papers. Hunt and Liddy burglarized the offices of Ellsberg's psychiatrist, looking for damaging information on the former Pentagon aide and military operative. Hunt recruited the break-in team through members of the Cuban expatriate community in Florida he knew from his time as a CIA agent working on the Bay of Pigs invasion. When some of those same Cuban expatriates were arrested in the Watergate complex, and when it was discovered that Hunt and Liddy were behind the Watergate break-in as well, Nixon sought desperately to cover up their earlier misdeeds.
In fact, it was his concern with those earlier transgressions that gave rise to a post-Watergate political axiom: that the cover-up of the crime can be more damaging than the crime itself. Nixon's creation of a secret police organization without congressional authorization -- one that carried out an illegal break-in without a warrant, no less -- would ultimately become a basis for one of the articles of impeachment brought against him by the House Judiciary Committee. As Howard Hunt would put it in an angry memo as his prosecution moved forward, "The Watergate bugging is only one of a number of highly illegal conspiracies engaged in by one or more of the defendants at the behest of senior White House officials. These as yet undisclosed crimes can be proved." Nixon's chief aide, Bob Haldeman, was caught on tape alluding to this very issue:
American President: Richard Milhous Nixon: Domestic Affairs