Amid the devastation left by World War II, Europe looked around after 1945 for a way to make sure such a disaster never happened again, and found an answer in the European Union. Over the next 50 years, the EU would become an unprecedented experiment in the pooling of national sovereignty and the falling of borders, a sophisticated system of transparency and mutual interference by independent nations in each other's economic and political affairs. As a result, Europe's once-warring nation-states are now so closely knit through the institutions, laws and councils of the EU that war across Western Europe has become unimaginable. "The European Union, despite hiccups along the way, has been an overwhelming success," said Craig Kennedy, president of the German Marshall Fund of the United States. "It has integrated a Europe that for centuries was at odds with itself, and homogenized it in a positive way with a common set of values and common outlook on the world." Yet for all the EU's success, the memory of a war half a century ago is fading, which threatens to stall or even unravel the Union. A united Europe failed to stop war on its borders in the Balkans in the 1990s. And when Secretary of State Condoleezza Rice of the United States visited Brussels in February and described a continent "unified around democratic values," where "the chances for war" would be "diminished and, indeed, eliminated," the rhetoric was jarring and strange to a European public that takes peace and democracy for granted, associating Brussels more with petty policy disputes and intrusive laws. Attitudes toward the EU are complicated by a growing view, in France, of the Union as a threatening face of globalization, and by Germans' re-examination of their historical guilt. A French rejection of the EU's new constitutional treaty in a national referendum on May 29 is not impossible. The Germans, in a new assertiveness, no longer want to be the biggest contributor to the EU's budget. If the EU is to survive, Europeans must remember the founding mission behind the glass towers in Brussels: an ever-closer union among the people of Europe, in the interests of security. Indeed, perhaps the most important achievement of what became known as the EU was the stability it brought in Western Europe's heartland between France and Germany. The real beginning came in 1950, with the announcement by Robert Schuman, the French foreign minister, of a plan by France and Germany, later joined by Belgium, Italy, Luxembourg and the Netherlands, to surrender power over their coal and steel industries, which had long provided the base elements of European militarization. Power was transferred to a new supranational High Authority, the future European Commission, under its first president, the Frenchman Jean Monnet. In announcing his plan, Schuman said, "The coming together of the nations of Europe requires the elimination of the age-old opposition of France and Germany." The 1957 Treaty of Rome took integration further, setting up the European Economic Community, a customs union. In the 1960s, the mechanics of the new community took clearer form with the emergence of the three distinctive institutions that now run the EU: the European Commission, which originates and enforces EU law; the European Council, which represents member governments; and the European Parliament, which holds the two other bodies to democratic scrutiny. After the first generation of Schuman, Monnet, Chancellor Konrad Adenauer of Germany and President Charles de Gaulle of France, came a new generation of French and German founding fathers: Helmut Schmidt and Valéry Giscard d'Estaing, Helmut Kohl and François Mitterrand, and Jacques Delors. They extended the EEC into new areas, such as the single market, the formal establishment of the EU, and, by 2002, the single currency, the euro. "The very early history of European integration was explicitly about stopping war," said Anand Menon, director of the European Research Institute at Birmingham University in England. "Even during discussions about European Monetary Union during the 1990s, Helmut Kohl warned that if we didn't get this next big step, then we would have war. This is what we needed to prevent us returning to the Dark Ages." Germans in particular adopted the cause of European integration as a source of a new identity, replacing, according to Stefan Wolff, professor of European studies at Bath University in England, "traditional German nationalistic identity." "Germany, a constant source of instability for several hundred years, has found a new identity for itself as part of a democratic structure in Europe," he said. The success of the project can be measured by the fact that Western Europe has seen no wars since 1945. The foreign ministers and grandees who a century ago confronted each other across Europe's chessboard now meet monthly and know each other well. There are fights, but they are diplomatic battles around the tables of Brussels rather than in the fields of Flanders. The stability has been exported, the EU extending geographically to admit countries such as Greece, Portugal and Spain in the 1980s. Nations without robust democratic traditions, they were taken into the West European fold and set on the road to democracy, as, even more dramatically, were the nations of the former East bloc that emerged from decades of Soviet domination and communism to join the EU in 2004. Since that enlargement, the biggest in the Union's history, the EU now includes more than 450 million people in 25 nations. But the EU cannot claim to have brought peace to millions on its own. One reason why Europeans were able to push ahead with closer cooperation on economic and social matters was that the much thornier problem of military and security cooperation was overseen by the North Atlantic Treaty Organization. "The security agenda, the really hard bit, was dealt with by the Americans," Menon said. Nor has the EU banished all the dark shadows from half a century ago. Germany is re-examining its past, questioning the historical guilt it has carried for six decades, even casting itself as a victim of some wartime atrocities. Recently, a film about Hitler prompted Germans to try to understand the appalling attraction and personal power of their former leader. Günter Grass looked at the plight of German refugees who died in the sinking of the Wilhelm Gustloff in his novel "Crabwalk." W.G. Sebald, in "On the Natural History of Destruction," considered the thousands who died in Allied bombardments of German cities. High unemployment in France and Germany and public uncertainty about how to deal with the effects of globalization are contributing to a growing hostility toward the EU in the Union's original heartland. This may be temporary, but if it leads to a rejection of the EU constitution in the French referendum this month, it could stall European integration or even unleash forces that begin to reverse it. A rejection would almost certainly jeopardize the efforts of countries like Turkey and Ukraine to join the EU. In an interview last month, Jean-Claude Juncker, prime minister of Luxembourg and current holder of the rotating EU presidency, warned that memories of World War II were fading and that if the EU was not cemented fully by the current political elite, then younger, future generations might lack the political drive to continue construction of an entity that, along with NATO, has brought peace to Europe. Juncker, a 20-year veteran of EU politics whose father was a soldier in the war, brings a perspective that may elude younger politicians. "I don't think the generation after us will be able to put together all those national biographies," he said, "in a way that the EU will not be split back into its national components - with all the dangers entailed."