One of the last mysteries of the Cold War is why so many seemingly intelligent Americans believed to the bitter end that the Soviet Union — history’s most vicious dictatorship and an economic basket case — was paradise on Earth.

Well, now we know.  In his new book Dupes, Paul Kengor provides a stunning, detailed exposé of how the Kremlin set out to manipulate those among us whom Lenin famously described as “useful idiots” — Americans who could be made to fall hook, line, and sinker for Soviet propaganda and who then used their influence to swing public opinion behind the Soviet Union’s policies.

Moreover — and perhaps even more importantly — Dupes exposes many of those among us who knowingly and willfully did the Kremlin’s duping. It’s quite a list. Did you know that Frank Marshall Davis, whom President Obama describes in his autobiography as his beloved mentor, was not merely a good-ole-boy who liked to bar-hop in Honolulu with Obama’s grandfather, but a card-carrying member — No. 47544, to be precise — of the Communist Party of the United States? (And did the president know it back when he sat at Davis’s knee out in Hawaii, learning about the world? Does the president know it now? Is there even a chance that some blown-dry White House reporter with teeth like Chiclets will ask?)

And did you know that another hardcore, card-carrying Commie was Howard Zinn, author of A People’s History of the United States, which to this day is among the most widely used textbooks in American high schools and colleges? (And does the principal of your kids’ high school know it? Would she take this clown’s book off the curriculum if she did?)

Dupes brilliantly outlines the Kremlin’s covert operations to gin up support for the USSR without tipping Moscow’s hand. For instance, Kengor shows how Lenin and his successors poured money into the CPUSA from 1919 all the way through the 1980s so that its members and affiliates in the U.S. could organize pro-Soviet demonstrations in our cities and buy space for Soviet propaganda in leading newspapers. (Well, who did you think paid for those full-page ads in The New York Times protesting President Reagan’s Strategic Defense Initiative?)

Kengor (a contributor to American Thinker, by the way) has done an extraordinary amount of research. His list of dupes suckered in by the Kremlin is astonishing. It includes leading intellectuals and writers like John Dewey, Upton Sinclair, Arthur Miller, and Benjamin Spock. And there were leading Hollywood stars including Gene Kelly, his wife Betsy Blair, and Humphrey Bogart. (Bogie caught on to the commies, fast, and publicly repudiated them; it took Gene Kelly a bit longer to figure it out.)

The things these dupes said and wrote about the Soviet Union are just amazing for their blind stupidity. For instance, after visiting the USSR in 1928, John Dewey, whose reputation as an educator remains legendary, wrote in The New Republic that the Bolshevik Revolution had been “a great success” and that the USSR’s churches “are not only intact, but taken care of with scrupulous and even scientific zeal.” Seventy years later, no less an authority than Mikhail Gorbachev acknowledged that at precisely the moment when Dewey was visiting Russia, Joseph Stalin had been waging “an all-out war on religion” in which churches were razed to the ground and clergymen arrested. Dewey, the Harvard dupe, never noticed.

The most explosive revelation in Dupes involves the late Lion of the Senate, Ted Kennedy. On May 14, 1983, just weeks after President Reagan launched the Strategic Defense Initiative, the head of the KGB, Viktor Chebrikov, sent a memo marked “Special Importance” to the Soviet Union’s leader, Yuri Andropov. Chebrikov reported that Kennedy wanted to meet with Andropov so the two men could coordinate their efforts to oppose SDI and, perhaps, defeat President Reagan in the upcoming 1984 election. As Chebrikov wrote, “Kennedy believes that, given the state of current affairs, and in the interest of peace, it would be prudent and timely to undertake the following steps to counter the militaristic policies of Reagan.” After outlining these steps, Chebrikov goes on to explain that “the main purpose of the meeting, according to the senator, would be to arm Soviet officials with explanations regarding problems of nuclear disarmament so they would be better prepared and more convincing during appearances in the USA.”

Simply put, Kennedy had set out to form a secret alliance with the leader of the Soviet Union to thwart United States policies — an act for which the precise, technical word is treason.

Dupes is a knockout. It’s first-rate history that reads like a first-rate espionage novel.