The Watergate complex in Washington, D.C., where the Democratic National Committee had its headquarters in 1972
For the Watergate burglars, the third try was the charm. Armed with an array of burglary tools, two of the Cuban-Americans on the team -- Virgilio Gonzalez and Frank Sturgis -- entered the building through the B-2 garage level. They climbed the stairs and taped open the doors behind them. Reaching the sixth floor where the DNC offices were located, Gonzalez made quick work of the door lock and the burglars were finally inside.
"The horse is in the house," they reported over a walkie-talkie back to team leaders across Virginia Avenue at a Howard Johnson's hotel. The leaders included G. Gordon Liddy, a former FBI agent who had devised the spying plan called Gemstone, and E. Howard Hunt, an ex-CIA officer and part-time spy novel writer.
At word that the break-in had finally succeeded, Liddy and Hunt embraced. From a balcony at the Howard Johnson's, James McCord, another former CIA officer and the security chief for the Committee to Re-elect the President known as CREEP, could see the burglars' pencil flashlights darting around the darkened offices. 
McCord, an electronics specialist, made his way over to the Watergate and was let in by one of the Cuban burglars. Upon reaching the DNC offices, McCord placed one tap on the phone of a secretary of Democratic National Chairman Larry O'Brien and a second on the phone of R. Spencer Oliver, a 34-year-old Democratic operative who was executive director of the Association of State Democratic Chairmen.
While some of the burglars rifled through DNC files and photographed documents, McCord tested the bugs on the two phones. His little pocket receiver showed that they worked. 
The choice of the two phones has never been fully explained. O'Brien's might seem obvious since he was party chairman, while Oliver was a well-placed insider in Democratic politics, though little known to the general public.
Some aficionados of the Watergate mystery have speculated that Oliver's phone was chosen because his father worked with Robert R. Mullen whose Washington-based public relations firm had employed Hunt. The firm also served as a CIA front in the 1960s and early 1970s, and did work for industrialist Howard Hughes, who, in turn, had questionable financial ties to Nixon's brother, Donald.
Because Oliver's father also represented Hughes, one theory held that Nixon's team wanted to know what derogatory information the Democrats might possess about money to Nixon's brother from Hughes, evidence that might be sprung during the fall campaign. 
After returning to the Howard Johnson's hotel from the Watergate, the burglary team's glow of success faded fast. The Gemstone team discovered that their receivers only could pick up conversations on one of the phones, the tap in Oliver's office. Though upset about the limited information that might flow from that single tap, the Gemstone team began transcribing the mix of personal and professional calls by Oliver and other members of his staff who used his phone when he wasn't there.
One of the Nixon operatives, Alfred Baldwin, said he transcribed about 200 calls, including some dealing with "political strategy," passing the transcripts on to McCord, who gave them to Liddy. The intercepts then went to Jeb Stuart Magruder, CREEP's deputy chairman who said he passed the material to reelection chairman and former Attorney General John Mitchell, who had left the Justice Department to run CREEP. 
Whatever other mysteries might surround the Watergate operation, one Gemstone goal was clear: to pick up intelligence on Democratic strategies as part of the larger plan to ensure that a weakened Democratic Party led by the least appealing candidate would face President Nixon in November 1972.
How useful the material turned out to be is another point in historical dispute. Since the intercepts violated strict federal wiretapping statutes, the contents were never fully disclosed and the recipients of the intercepts had both legal and political reasons to insist that they either hadn't seen the material or that it wasn't very useful.
Magruder said Mitchell personally chastised Liddy over the limited political value of the information. Some of the material was little more than gossip or personal details about the break-up of Oliver's marriage. "This stuff isn't worth the paper it's printed on," Mitchell told Liddy, according to Magruder. Mitchell, however, called Magruder's account "a palpable, damnable lie."
What They Got