Germany’s dilemma is that it has to set the terms for Europe’s integration without jeopardizing its unity.

Today’s Germany emerged in 1990 when the formerly communist East Germany was incorporated into the Federal Republic. Nearly half a century of disunion had left an economic and social divide in the country that took more than two decades to mend — and some imbalances remain. Historically, however, the more pertinent geographical divide in Germany has been between its north and south.

The northern half of Germany is situated on the North European Plain which stretches from what is today Poland into the Netherlands. Some of these lands were once part of Germany and all are economically integrated with it today.

The northern rivers, including the Elbe, Oder and Weser, flow northward, facilitating this part of Germany’s integration with the Baltic and North Sea regions.

Agriculture in the north is highly rationalized with large and prosperous farms dotting the flat landscapes of Lower Saxony, Schleswig-Holstein and Westphalia. Farmers in the region have historically been more export-oriented and the loss of the great grain and livestock producing estates of Prussia after the Second World War necessitated economies of scale.

Southern farms are smaller, inhibited by the hilly terrain as well as Napoleonic inheritance laws that divided lands evenly between a farmer’s sons. Protectionist agriculture laws enabled these farmers to stay in business until after the war when many were forced to take second jobs, often in industry.

The north is home to by far Germany’s most populous state, North Rhine-Westphalia, which is the heart of its heavy industry. Its major cities line the Rhine River whose valley cuts through the western part of the Central Uplands that separate the Northern Lowland from the hills and Alps in the south and which empties into the North Sea at Rotterdam, one of the world’s busiest ports.

The only deepwater port in Germany itself is Wilhelmshaven which also hosts its only oil import terminal. Pipelines from there supply refineries in Hamburg and North Rhine-Westphalia’s Rhine-Ruhr conglomeration. After Russia, Germany is the second largest refiner in Europe. But it has no liquefied natural gas terminals and is dependent on pipeline imports from the Netherlands, Norway and Russia.

During the 1970s and 1980s, the north experienced an economic decline as modern industries descended on the south. Attracted by lower labor costs and lower taxes in its politically conservative regions, glossy new aerospace, car and robotics plants, often medium-sized and family owned, nestled in the sloping countrysides of Baden-Württemberg and Bavaria while the “rustbelt” north was left with closed shipyards and steelworks, polluting oil refineries and restless trade unions.

This Nord-Süd-Gefälle actually mended an economic divide that had previously been to the advantage of the north. Trade centers like Bremen and Hamburg, as well as Berlin, have since imitated the south’s focus on high technology and employed more workers in services.

Competition between the highly autonomous Länder and Germany’s big cities stems from its long division into different sovereign states. Prussia, which had come to occupy virtually the whole of the North European Plain during the Napoleonic Wars, including today’s northern and western Poland as well as Russia’s Kaliningrad province, was by far the most powerful. Its prime minister, Otto von Bismarck, forged an empire out of the many German kingdoms and principalities in 1871.

This unified Germany was vulnerable to invasion as the Great European Plain extends into the west of France and Russia to the east. Therefore, Bismarck’s strategy was to prevent an alliance between France and Russia that could destroy his country. Yet unification drew the other continental powers together. Where the German states had previously acted as a useful buffer between Austria, France and Russia, the united Germany could conceivably defeat its adversaries separately.

When France and Russia allied in the early twentieth century, Germany’s recourse was to attack them both and try to defeat France before fighting Russia. This strategy failed in the First World War when Germany ended up fighting a war on two fronts it could not win. It managed to defeat France during the Second World War but got bogged down in Russia, giving its other enemies time to mount a counterattack from the west.

To prevent the reemergence of a Germany that America’s former secretary of state Henry Kissinger famously said was “too big for Europe,” the allies, after World War II, divided it. West Germany was effectively reduced to a Rhine Confederation that, sans Prussia, had been a client state of Napoleonic France’s. East Germany became a Soviet vassal. West Germany was further ensconced in a European and transatlantic economic and security framework, through NATO and what would become the European Union, that allowed it to prosper economically without posing a military threat to its neighbors. With Germany on par with France, the European balance of power that had been frantically sought throughout the nineteenth century seemed to have been finally achieved by abandoning the game of shifting alliances.

Reunification in 1990 revived the German problem geopolitically but the nation had been so thoroughly pacified in the preceding half century that it could hardly be expected to pose a security threat.

Nevertheless, as it has taken a central role in solving the European currency and debt crisis, the Franco-German parity is increasingly an illusion and fears of German domination have resurfaced, especially in those European Union member states that now depend on the nation’s financial support.

As Europe’s central power and largest economy, Germany is the only country that can set the terms for its future political integration. Its dilemma is that it has to guide that process, to secure access to markets for its industrial surpluses, while preventing an alliance from rising against it that would jeopardize European unity.