Between 1864 and 1871, Otto von Bismarck — Prussian minister-president, conservative, master of Realpolitik — fought three short wars (against Denmark, Austria, and France) and welded thirty-eight independent German states into a single empire under Prussian leadership. He had told the Prussian parliament in 1862 that the great questions of the age would be settled not by speeches and majority votes but by blood and iron; he meant it. The German Empire he proclaimed in the Hall of Mirrors at Versailles in January 1871 — pointedly, in the conquered palace of the French kings — was the most powerful continental state Europe had seen since Napoleon, and its mere existence destabilized the European balance of power for the next seventy-five years.
Bismarck's method was war as instrument of state-building, applied with calibrated cynicism. Each war was limited, winnable, and productive of a specific political effect: the war against Denmark (1864) established Prussian leadership of the German question, the lightning war against Austria (Königgrätz, 1866) excluded the Habsburgs from German politics and dissolved the old German Confederation, and the war against France (1870–71), triggered by his doctored Ems Dispatch, produced the patriotic surge that swept the southern Catholic states into a Reich led by Protestant Prussia. Then Bismarck pivoted entirely. The man who had made Germany by war became Europe's most cautious diplomat, declaring the empire satiated and building an elaborate alliance system — the League of the Three Emperors, then the Dual and Triple Alliances — to keep France isolated and prevent any coalition forming against Berlin. At home he governed through manufactured enemies: the Kulturkampf against the Catholic Church, then the anti-socialist laws against the Social Democrats. Yet he also pioneered the welfare state (sickness insurance 1883, accident insurance 1884, old-age pensions 1889) precisely to cut the ground from under those same Social Democrats and bind the working class to the throne. The structure depended on his hand. After the young Kaiser Wilhelm II dismissed him in 1890, his successors kept the war instinct without the restraint — let the reinsurance treaty with Russia lapse, launched a naval race with Britain, and so summoned the very encircling coalition Bismarck had spent twenty years preventing. The result, a generation on, was 1914.
The German Question — what to do about a powerful Germany at the centre of Europe — was the structural problem behind two world wars. The current European Union, in which Germany is economically dominant but politically bound by integration with France and the smaller states, and embedded in NATO, is the fourth or fifth attempt at a stable answer, after Versailles, partition, and the Cold War's divided Germany each failed or expired. So far it has held — a reunified Germany that anchors a union rather than threatening one, exporting goods rather than armies. The achievement is easy to take for granted, which is exactly why it is fragile.