When Germany invaded Poland, on September 1, 1939, the date that W. H. Auden used for his famous poem—“I and the public know / What all schoolchildren learn, / Those to whom evil is done / Do evil in return”—Poland had commitments in hand from France and Britain to come to its aid if its independence was threatened. In Warsaw, in the first week of September, enthusiastic crowds gathered outside the French and British Embassies. They expected that Berlin would be bombed and that British and French forces would attack Germany from the west.

But the British and the French did neither of those things, and the war did not take long. On September 27th, Warsaw surrendered to the Germans. Meanwhile, on September 17th, pursuant to an agreement between Stalin and Hitler, Poland was invaded from the east by the Red Army. That campaign lasted less than a month. By October, Poland was in the hands of its two ancient enemies.

For the next five years, those enemies did their best to destroy it. And then, for forty-five years after that, Poland found itself locked in a totalitarian cage whose key was kept in Moscow. No one had come to the rescue of Poland in 1939, and no one came to its rescue after 1945. In the end, Poland had to rescue itself.

The Polish story is the heart of Anne Applebaum’s remarkable book, “Iron Curtain: The Crushing of Eastern Europe” (Doubleday), a book that reanimates a world that was largely hidden from Western eyes, and that many people who lived and suffered in it would prefer to forget.

Although eastern Poland was one of the most impoverished areas in Central Europe, it was better off than the Soviet Union. As soon as the Soviets gained control of it, in 1939, they looted whatever they could get their hands on. Representatives of the People’s Commissariat for Internal Affairs (also known as the N.K.V.D., predecessor of the K.G.B.) carried out an extermination program targeting the Polish élite.

In the most notorious case, almost fifteen thousand Polish officers, most of them professionals in the reserve corps, were arrested and deported. More than four thousand were shot and buried in a forest outside Katyn, in western Russia. The rest went to special camps. Fewer than five hundred were ever heard of again. In all, 1.2 million Poles were deported to the U.S.S.R. by the Soviets from their half of Poland, an area with a population of thirteen million. Half of them died in captivity.

In the west, Hitler embarked on his plans to Germanize the country by ridding it of Jews, driving out the Slavic population, and resettling the land with Volksdeutsche. All the major Nazi death camps were situated in annexed or German-occupied Poland. Of the estimated 5.7 million European Jews killed in the Holocaust, some three million were Polish—ninety per cent of all the Jews in Poland. Although the British and the Americans knew of the extermination camps, they refused to bomb the railroad tracks used to transport the victims.

To Stalin’s astonishment, in June, 1941, Germany invaded the Soviet Union, the start of what Russians call the Great Patriotic War, which trapped Poland and the other nations of Eastern Europe in the middle of what Hitler planned as a Vernichtungskrieg—a war of extermination, a war without rules, total war.

After nearly losing Moscow, the Red Army turned the tide and pushed the Germans back through the lands they had conquered: Hungary, Romania, Czechoslovakia, Bulgaria, and Poland, countries that were thus invaded twice in five years. As the Red Army “liberated,” it plundered, or disassembled and sent to the Soviet Union, virtually everything of value, from wristwatches to steel factories. The N.K.V.D. mopped up by deporting or executing “anti-Soviet elements”—those among the local partisans and nationalist political groups who had managed to survive the similar extermination policies of the Einsatzgruppen.

When the Red Army reached Poland, in the summer of 1944, it waited on the banks of the Vistula, just outside Warsaw, while the S.S., under the direction of Heinrich Himmler, killed fifteen thousand Polish partisans, who had staged an armed uprising, and more than two hundred thousand civilians. At the end of the fighting, half a million Poles were sent to camps, and the rest were deported as slave laborers to Germany. On Hitler’s orders, the city was razed. When the Red Army finally entered Warsaw, in January, 1945, the streets were filled with dead bodies. No one living remained.

Except in Bulgaria, which has cultural ties to Russia, Soviet soldiers not only looted but raped, almost systematically, in the countries they passed through. In eastern Germany alone, up to two million women are believed to have been raped by Soviet soldiers. But, apart from complaining about Stalin’s refusal to come to the aid of the Warsaw Poles, Britain and the United States did nothing to stop the pillage of Eastern Europe.

Before the war in Europe ended, in May, 1945, the Soviets had already begun to establish “people’s democracies” in the countries of Eastern Europe. When Winston Churchill gave his Iron Curtain speech, in March, 1946, it was clear that Stalin had no intention of withdrawing from Eastern Europe, or of allowing regimes unfriendly to the Soviet Union to install themselves there. A year later, President Truman delivered the speech that announced the Cold War. In a world divided between democratic and totalitarian states, he told a joint session of Congress, it would be the policy of the United States “to support free peoples who are resisting attempted subjugation by armed minorities or by outside pressures.”

This warning had no effect on the countries of Eastern Europe. For the next six years, the Soviets, using tactics of intimidation, imprisonment, execution, assassination, election rigging, and show trials, eliminated all political opposition. It turned those nations into one-party states and installed puppet regimes. This was not done with any great subtlety. Eleven months after Truman’s speech, in February, 1948, Czech Communists staged a coup and threw the Foreign Minister, Jan Masaryk, out a window of the Czernin Palace.* The United States did not intervene.

Despite occasional talk of “liberation” and “rollback,” non-intervention remained American policy toward Eastern Europe throughout the Cold War. Strikes and protests in East Germany in 1953 and Poland in 1956 were violently suppressed, and, although the strikers had hoped otherwise, the United States did not get involved.

Protests in Hungary in 1956 turned into a full-scale revolution, and the Soviet-backed government was overthrown. The Red Army invaded. More than two thousand Hungarians were killed, two hundred thousand fled the country, and the leader of the new government, the reform-minded Communist Imre Nagy, was arrested, tried in secret, and hanged, as an example to other deviationists. These revolutionaries, too, had expected help from the West, but help never came. The American government assured the Kremlin that it had no national interest at stake in Hungary. When some people complained that Radio Free Europe had been urging Hungarians to resist Soviet domination for years, Eisenhower pointed out that the United States had never advocated violent resistance.

The United States did nothing to stop construction of the wall that encircled West Berlin in 1961, except to compel the Soviets to agree that, in principle, Western movements anywhere inside the city would not be impeded. That principle was never tested. In August, 1968, five hundred thousand Warsaw Pact troops invaded Czechoslovakia and, a few months later, overthrew the reformist government of Alexander Dubcek. (Auden used the date of the invasion as the title of another poem, which begins, “The Ogre does what ogres can, / Deeds quite impossible for Man, / But one prize is beyond his reach: / The Ogre cannot master Speech.”) No Western power interfered.

Nor did the United States or any other democratic nation play a significant role, beyond cheerleading, in the Velvet Revolution, in 1989, which led to the overthrow of Communism and the collapse of the Soviet empire. For forty-five years, the Soviets were allowed to have their way in Eastern Europe, a state of affairs that was generally officially ignored, and sometimes even officially denied. In 1976, President Gerald Ford, who had been in Washington for twenty-seven years, claimed, in a debate with Jimmy Carter, that “there is no Soviet domination of Eastern Europe.” (He later clarified this by saying that Eastern Europeans did not feel dominated.)

This grant of immunity gave the Soviet Union a free hand to carry out one of the most radical experiments in social engineering in history. Between 1945 and 1953, the year that Stalin died, the societies of Eastern Europe were remade from top to bottom. The goal was not to force people to serve a new political system. The goal was to produce a new kind of human being, a human being who would not need to be forced to serve the system. The creation of that new human being was the end that justified every means, and those means are the subject of Applebaum’s book: how the Soviets and their local apparatchiks attempted to build the perfect socialist world.

Applebaum’s previous book was “Gulag: A History,” published in 2003. It gave names and faces to a numbing statistic. Between 1929, when Stalin had firmly consolidated his position as Lenin’s heir, and 1953, eighteen million people were sent to labor camps in the Soviet Union. More than two million died there. Applebaum used memoirs and oral testimony to give a picture of how the Gulag worked—what it was like to be caught in the insatiable maw of Stalinist purgation, to be arrested, transported, incarcerated, abused, and, for the lucky, after many years, released. She helped to humanize an inhumanity.

The new book is a re-creation of life on the streets and in the prisons of Poland, Hungary, Czechoslovakia, Romania, Bulgaria, Yugoslavia, and East Germany in the years of Stalinization. “Iron Curtain” gives us some idea of what it was like to be trapped in the Soviet experiment, to be a witness to the demolition and reconstruction of one’s environment. Applebaum wants to give flesh to a concept. “I sought to gain an understanding of real totalitarianism, not totalitarianism in theory, but totalitarianism in practice,” she says.

The term originated in Italy. According to Abbott Gleason, in his standard history of the concept, “Totalitarianism: The Inner History of the Cold War” (1995), it was first used, in 1923, by an opponent of Benito Mussolini, who referred critically to the Fascist government as a “sistema totalitaria.” Mussolini didn’t mind at all. By 1925, he was referring proudly to “la nostra feroce volontà totalitaria”—“our fierce totalitarian will.” By “totalitarian,” he meant a politics that aimed at the total transformation of society.

In Nazi Germany and in the Soviet Union, the agent of this transformation was not the state. It was the party. The state, especially the judiciary, was simply the party’s bureaucratic dummy. This was because the purpose of totalitarian transformation was not mere efficiency—“making the trains run on time,” as people used to say of Fascist Italy. Nor was it the enjoyment of power for power’s sake, as many representations of totalitarian regimes, such as George Orwell’s “Nineteen Eighty-four,” suggested. The purpose was the realization of a law of historical development, the correct understanding of which was a monopoly of the party. In Hitler’s Germany, life was transformed in the name of a single goal: racial purity. (“The state is only a vessel,” Hitler wrote, in “Mein Kampf,” “and the race is what it contains.”) In the Soviet Union, it was done in the name of the classless society and the workers’ state.