Before Secret Service agents guarded the president, they chased counterfeiters. Their assignment did not formally shift until 1894, when a handful of agents served as Grover Cleveland's bodyguards. But there is an earlier example of the Secret Service getting involved in presidential security, albeit briefly, and in a posthumous kind of way.

In 1876, Abraham Lincoln's body lay within an aboveground white marble sarcophagus in a handsome tomb on the grounds of Springfield, Ill.'s Oak Ridge Cemetery. Oak Ridge was a rural cemetery located about 2 miles outside of the town. No groundskeeper lived there. No night watchman patrolled the area around the president's tomb. And the only thing standing between Lincoln's body and any would-be grave robbers was a single padlock on the tomb's chamber door. Not even the president's sarcophagus was burglarproof: Its lid was sealed, not with cement but with the less permanent plaster of Paris. To the distinguished gentlemen of Springfield who were members of the National Lincoln Monument Association, the organization charged with maintaining Lincoln's tomb, the absence of rigorous security measures seemed perfectly reasonable. After all, who would want to steal Lincoln's body?

Comic caper. The answer to that question was a gang of Chicago Irish counterfeiters led by a small-time crime boss named Big Jim Kennally. Early in 1876, Kennally's best engraver of counterfeit plates, Benjamin Boyd, had been sentenced to 10 years in the state penitentiary in Joliet, Ill. To pressure the governor to release his man, Kennally recruited two members of his gang, Terence Mullen, a saloonkeeper, and Jack Hughes, a sometime manufacturer of counterfeit nickels, to kidnap Lincoln's body. For ransom, they would demand $200,000 in cash and a full pardon for Boyd.

Given the cemetery's minimalist approach to security, the gang actually had a better-than-even chance of pulling off the heist. But they made a significant mistake. Neither Mullen nor Hughes had any body-snatching experience, so they invited a man named Lewis Swegles, who they thought was a grave robber, to help them. They couldn't have made a worse choice, because Swegles was a paid informant—a "roper"—of the Secret Service.

Swegles played his part as double agent well, reporting every detail of the plot to his boss, Patrick D. Tyrrell, chief of the Chicago district office of the Secret Service. On the night Swegles accompanied Mullen and Hughes to Oak Ridge Cemetery, Tyrrell and his agents were lying in wait for them at Lincoln's tomb, witnesses for the comedy of errors that soon began. Although Mullen and Hughes were career criminals, they couldn't pick a lock, so they had to cut through the padlock with a file. Once inside the tomb chamber, they found they could not lift Lincoln's 500-pound cedar-and-lead coffin. The inept grave robbers were considering their options when a detective's pistol accidentally went off outside. Mullen and Hughes bolted, but it wasn't much of a getaway—they headed straight back to their saloon in Chicago where Tyrrell arrested them a couple days later.

Meanwhile, back in Springfield, the custodian of the tomb, John Carroll Power, was in a state of panic. If hapless amateurs could come so close to carrying off Lincoln's body, what would happen if professional body snatchers targeted the tomb? The only solution Power could think of was to hide the body where no one could find it. So after dark, Power and five friends buried Lincoln in a shallow, unmarked grave in the tomb's basement.

Code of honor. None of the men who buried the coffin that night had known Lincoln. They were ordinary guys—one was a railroad ticket agent, another was a hotelkeeper, and a third worked as a bank clerk. Yet it had fallen to them to safeguard the remains of Lincoln, and they took that obligation seriously, swearing never to reveal the location of the martyred president's body. And in the years that followed, they kept that secret faithfully.

They were finally relieved of their obligation in 1901, when, under instructions from Robert Lincoln, the president's only surviving child, Lincoln's body was placed inside a steel cage, lowered into a 10-foot-deep vault, and buried under tons of wet concrete. He's still there, in his tomb on the grounds of Oak Ridge Cemetery.

While Tyrrell was the undisputed hero of the hour, the Secret Service perhaps benefited most of all from the failed crime. Protecting Lincoln's body led them to protecting the office of the presidency.