The plot to link JFK's death and Watergate.

In November 1973, on the 10^th anniversary of John F. Kennedy's assassination in Dallas, the New Left muckraking magazine Ramparts ran a long essay titled "From Dallas to Watergate: The Longest Cover-Up." The author, Peter Dale Scott, a professor at the University of California at Berkeley, put forth the idea that Kennedy's murder and the scandals then engulfing the Nixon administration were linked. Though a reader could search the article in vain for any direct connection, Scott made much of the hints of what he called a "sinister overlapping of conspiracies." Noting that key players in both incidents had ties to organized crime and U.S. intelligence networks, he claimed that secret American efforts to kill Fidel Castro held the key to an ongoing massive cover-up.

In late 1973 theories like Scott's were proliferating. From that historical vantage point, the twin traumas of Dallas and Watergate seemed to bracket a decade of disorientation and dashed promise. Many Americans, wondering how an era ripe with hope could devolve so fast into turmoil and crisis, began to reach for conspiracy theories to explain where "the '60s" had gone awry. This was the moment, with dreams of revolution (or merely reform) now dead, when outlandish notions about Kennedy's death—and, more important, a cynicism about the workings of American democracy—took root.

Elaborate speculations about Kennedy's murder had begun, of course, earlier—almost from the moment he was shot. Shock and grief, along with lingering mysteries surrounding the killing and the gunman, Lee Harvey Oswald, stoked doubt that a lowly maniac could really snuff out such an august leader. But what started as normal human disbelief evolved in the next decade into a conscious program of radical skepticism, especially among the ranks of the New Left.

From authors like Mark Lane and Edward Jay Epstein (whose 1966 books poked holes in the official Warren Commission Report holding that Oswald had "acted alone") to New Orleans District Attorney Jim Garrison (who in 1967, amid much fanfare, indicted a local businessman in the alleged plot), assassination sleuths imagined a rogue's gallery of villains—Soviet agents, CIA operatives, Mafiosi, oil barons, Fidel Castro, even Lyndon B. Johnson—enmeshed in the intrigue.

Garrison's failure to convict his suspect set back the nascent conspiracy movement. But soon the all-too-real secret plotting of the Nixon administration revived speculation. "With Watergate, in '73 and '74, you start to see a new wave of theorizing about it," said Max Holland, who is completing a history of the Warren Commission. "Groups start springing up independently, looking backward at the assassination through the lens of Watergate." Watergate, after all, was a conspiracy—a grand jury named the president an "unindicted co-conspirator"—and the crisis seemed to validate the worst suspicions about the dark machinations of government officials.

It only whetted suspicions that certain people and places from assassination lore resurfaced in the Nixon saga. It turned out that Nixon had visited Dallas the day before Kennedy's assassination—his law firm represented Pepsi-Cola, whose bottlers were meeting there—and the coincidence piqued those who were inclined to implicate Tricky Dick. Skeptics pounced, too, on learning that some of the men who burgled the Democratic Party headquarters in June 1972 had participated in the abortive invasion of Cuba at the Bay of Pigs 11 years earlier. And when Nixon's successor, Gerald R. Ford, pardoned the ousted president in September 1974, conspiracists, aware of Ford's service on the Warren Commission, concluded that the new chief executive was simply sealing the grand cover-up once more.

Some, enterprisingly, sought to link Dallas and Watergate in a single octopus-like plot. Mae Brussell, a Stanford graduate, had spent much of the 1960s cross-referencing the 26-volume Warren Report into a 27,000-page concordance, according to Paul Krassner, then editor of the underground paper the Realist. (Now deceased, she still inspires assassination buffs who call themselves "Brussell Sprouts.") When she heard about the fateful break-in, she recognized certain names and affiliations from her research and banged out a 21-page article for the August 1972 issue of the Realist. As in Peter Dale Scott's Ramparts piece, the exact argument was hard to find. But the thrust was clear: that a clandestine government serving the interests of military and industrial hard-liners had murdered Kennedy and was responsible for the Nixon scandals then coming to light.

If Brussell was the first writer to link Dallas and Watergate, the most earnest was the New Left activist Carl Oglesby, who hoped to solve, as he put it, "not just the murder mystery but the political mystery." A former president of Students for a Democratic Society, Oglesby was devastated by the organization's implosion in 1969. In the Watergate years he moved to Cambridge, Mass., where he founded a group called the Assassination Information Bureau that sought "to politicize the question of John F. Kennedy's assassination." The bureau's activism helped bring about a congressional committee that in 1979 concluded, on the basis of acoustic evidence, that a second gunman had in fact shot at Kennedy (although later findings cast doubt on that conclusion).

The congressional committee, alas, did not endorse Oglesby's larger theory, what he called "a drama of coup and countercoup" that stretched from Dealey Plaza to the Nixon White House. In The Yankee and Cowboy War (1976), Oglesby posited two oligarchic cabals of businessmen, once allied in supporting the Cold War, that split in the 1960s over Vietnam and Cuba. The "Yankees," old-money Northeastern businessmen and liberal internationalists, had begun to oppose the Indochina war and soften their hostility toward Castro. In contrast, the "Cowboys," the extreme anti-communist real-estate and oil moguls of the Southwest, wanted to keep expanding America's economic frontiers in Asia. In Oglesby's theory, the Cowboys killed Kennedy because of his timidity in foreign policy and supported Nixon; but eventually the Yankees, through the CIA, struck back and sabotaged the Watergate break-in to bring Nixon down. "Kennedy was offed so that Vietnam could be escalated," Oglesby said. "Nixon was offed so that Vietnam could be brought to a close."

Oglesby's journey from New Left activist to full-time assassination buff was emblematic of a trend. While some radicals abandoned politics in the '70s to take up personal searches for meaning, others sought answers in sorting out the disaster-ridden history of recent times, trying to explain what went wrong. Baroque conspiracy theories, illustrating how a power elite blocked avenues for radical change, promised to restore logic to the broken narrative of the 1960s.