IN THE EUPHORIC FIRST WEEKS after the fall of the Berlin Wall, East German protesters who had risked everything to overthrow their government and were now jockeying for position in the emerging new Germany were puzzled by a growing number of news reports from the other side of the Atlantic.

American conservatives, they kept hearing, were claiming credit for ending the Cold War and “liberating” them from the yoke of Soviet communism.

They were puzzled not just because the names of these conservatives — Gingrich, Buchanan, Kemp — were unfamiliar. What baffled them was more fundamental: they hadn’t received American help at all. The CIA, by its own later admission, was entirely absent during the long months and years when East German dissidents organized covert meetings in churches and semi-derelict apartment buildings, usually no more than a step or two ahead of the Stasi, the all-pervasive secret police.

No Americans had helped the protesters organize a massive rally on the 40^th anniversary of East Germany’s founding, on October 7, 1989, which embarrassed the leadership in the presence of the visiting Soviet leader, Mikhail Gorbachev. It was not the Americans, but rather a coalition of civic leaders, including the celebrated conductor Kurt Masur, who negotiated a truce in Leipzig two days later and convinced the security forces not to open fire on the 70,000 people in the crowd. Many of the officers, who had been given live rounds and instructed to emulate the Chinese massacre in Tiananmen Square if necessary, put down their weapons and joined the protests instead.

I was in Leipzig as a young reporter just a few days after the Wall fell on November 9, and remember being struck by the hundreds of thousands of people filling the town center on a freezing winter’s night, and the enormous pride they expressed as they pushed to topple the regime. This was their victory, the triumph of “people power,” and they had done it overwhelmingly by themselves. The only discernible American presence was the Tracy Chapman song “Talkin’ Bout a Revolution” blaring from loudspeakers in the market square.

And yet, back in the United States, a mythology took hold. Ronald Reagan had set this train in motion, the narrative went, because he had gone to the Berlin Wall in June 1987 and fearlessly told Gorbachev to “tear down this Wall.” And now it had happened. The mythology grew strong enough over time that many people developed the erroneous impression Reagan was still president when the Wall came down. (In fact, he had been replaced 10 months earlier by George H.W. Bush.)

Reagan himself traveled back to Berlin in late 1990 and gave a speech congratulating himself on engineering the end of the Cold War. His signal achievement, he said, had been the decision to station nuclear cruise missiles in West Germany and his pursuit of the Strategic Defense Initiative, the missile shield program also known as Star Wars. But this, as Berliners knew better than anybody, was a convenient and self-serving rewrite of history. It was not true, as Reagan and other conservatives liked to argue, that aggressive increases in military spending had caused the Soviet empire to bankrupt itself as it scrambled for a response; the Soviet economy was already in tatters when Reagan took over, and there was no evidence of significant change in Soviet military spending in the 1980s. Reagan’s 1987 visit to Berlin had been a diplomatic near-...