Why were people cheering and dancing and drinking champagne atop the Berlin Wall on the evening of Nov. 9, 1989?

Because the ugly concrete and barbed-wire barrier that had divided Berlin for more than 28 years was at last open. Thousands of East Berliners -- and then hundreds of thousands -- surged into West Berlin.

The fall of the Berlin Wall marked the end of communism in East Germany and by the end of the year all of East Europe.

Why should we Americans celebrate the 20th anniversary of that evening? Because the opening of the wall meant that the Cold War was effectively over, and the many sacrifices in life and treasure that we had made over the decades, including the Korean and Vietnam Wars, were justified.

The Berlin Wall came tumbling down just two years after President Ronald Reagan, standing before the Brandenburg Gate, challenged Soviet leader Mikhail Gorbachev to "tear down" the wall and seven years after his bold prediction, to the British Parliament, that Marxism-Leninism was headed for the "ash heap of history."

Reagan was no longer in the White House when the wall fell. But when he visited Poland in 1990, a dissident leader presented the former president with a sword as thousands of Poles roared their approval. "I am giving you the saber," the Polish leader said, "for helping us to chop off the head of communism."

On that November evening 20 years ago, people were celebrating the collapse of communism not only in Berlin but in cities all over East Europe -- in Warsaw, Prague, Budapest and other capitals.

No longer would they have to bow down to tyrants like Lenin, Stalin, Khrushchev, Brezhnev and their local clones.

No longer would they wait in fear for the secret police to knock on the door in the middle of the night.

No longer would they be subject to purges, show trials and summary executions.

No more would they face forced famines, gulags or imperial adventures in far-off places.

No longer would they be denied open elections, multiple parties, free assembly, a free press and an independent judiciary.

No longer would they be obliged to join the Communist Party to shop in a well-stocked store, live in a comfortable apartment, or send their children to a decent school.

No more would they have to listen to gullible Western visitors who after one week in a communist country prated that they had seen the future and it works.

Now they could start a business of their own or join an independent union.

They could say grace before meals and go to a church or a cathedral or a synagogue of their choosing.

They could write a book or a poem, or a play or a song, or conduct a scientific experiment without the approval of a suspicious censor.

They could publicly honor heroes of freedom like Vaclav Havel, Lech Walesa, John Paul II, Vytautas Landsbergis and Pastor Tureck, who sparked the mass East German demonstrations leading up to the fall of the Berlin Wall.

During the 28 years it stood, more than 5,000 people successfully crossed the wall to freedom. About 3,200 people were arrested in the border area attempting to do so. At least 136 people were killed, and another 120 injured, seeking freedom.

Another 750 freedom-seekers lost their lives along the entire length of the Iron Curtain. According to the authoritative Black Book of Communism, some 1 million people perished as a result of communist terror in all of East Europe beginning in the 1940s.

A key factor in the winning of the Cold War: millions of American military personnel who served in West Germany and elsewhere in West Europe. They provided the military muscle for the policy of containment -- which President Harry Truman initiated in 1947 -- that prevented the Soviets from gaining control of West Europe as they had East Europe in the wake of World War II.

For more than four decades, American soldiers did the hard training and conducted the military exercises that kept them battle ready. They formed a study line of defense that the Soviets and Warsaw Pact forces never dared cross.

This is why we should mark the 20th anniversary of the fall of the Berlin Wall. To celebrate the collapse of communism. To honor those who died resisting communism. And to resolve that never again will peoples and nations allow so evil a tyranny to terrorize the world.

Lee Edwards is a Distinguished Fellow in the B. Kenneth Simon Center for American Studies at The Heritage Foundation.