The German Empire (German: Deutsches Reich), also referred to as Imperial Germany or the Second Reich, was the period of the German Reich from the unification of Germany in 1871 until the November Revolution in 1918, when Germany changed its form of government to a republic. The German Empire consisted of 25 states, each with its own nobility: four constituent kingdoms, six grand duchies, five duchies (six before 1876), seven principalities, three free Hanseatic cities, and one imperial territory. While Prussia was only one of the four kingdoms in the realm, it contained about two-thirds of the Empire's population and territory, and Prussian dominance was also constitutionally established, since the king of Prussia was also the German Emperor (Deutscher Kaiser).
The empire was founded on 18 January 1871, when the south German states, except for Austria, Switzerland and Liechtenstein, joined the North German Confederation. The new constitution came into force on 16 April, changing the name of the federal state to the German Empire and introducing the title of German Emperor for Wilhelm I, King of Prussia from the House of Hohenzollern. Berlin remained its capital, and Otto von Bismarck, Minister President of Prussia, became chancellor, the head of government. During its 47 years of existence, the German Empire became an industrial, technological, and scientific power in Europe, and by 1913, Germany was the largest economy in continental Europe and the third largest in the world. The success of the German Empire in the natural sciences was such that one-third of all Nobel Prizes went to German inventors and researchers. Germany also became a great power, building Europe's most extensive rail network, the world's strongest army, and a fast-growing industrial base. Starting very small in 1871, in a decade, the navy became second only to Britain's Royal Navy.
Otto von Bismarck served as the first and longest-tenured chancellor of the German Empire from 1871 to 1890. His tenure began with relatively liberal measures and broad reforms but gradually shifted toward conservatism, marked by the Kulturkampf against the Catholic Church. In foreign affairs, Bismarck concluded the Dual Alliance with Austria-Hungary in 1879 and fostered close ties to the Ottoman Empire; the former expanded into the Triple Alliance with Italy in 1882. Despite denouncing liberals and socialists as "enemies of the Reich", he introduced pioneering social programs that laid the foundation for the modern European welfare state. In the 1880s, Germany entered the colonial race despite Bismarck's earlier reluctance, acquiring territories in Africa, the Pacific, and China and building the world's third-largest colonial empire after the British and French. Following Bismarck's dismissal in 1890, Wilhelm II pursued Weltpolitik ("world politics"), a more aggressive and expansionist course that abandoned Bismarck's complex alliance system, leaving Germany increasingly isolated. When the July Crisis of 1914 escalated into the First World War, Italy distanced itself from the Triple Alliance while the Ottoman Empire aligned with Germany. The emperor's inconsistent and often unpredictable decisions contributed to the tensions that culminated in the outbreak of the war.
In the First World War, German plans to capture Paris quickly failed, and the war on the Western Front became a stalemate. The Allied naval blockade was a major contributing factor in the severe shortages of food and supplements. However, Imperial Germany had success on the Eastern Front; it occupied a large amount of territory to its east following the Treaty of Brest-Litovsk. The German decision to restart unrestricted submarine warfare in early 1917 contributed to bringing the United States into the war. In October 1918, after the failed Spring Offensive, Germany's armies were in retreat, its allies, Austria-Hungary and the Ottoman Empire, had collapsed, and Bulgaria had surrendered. The empire collapsed in the November 1918 Revolution with the abdication of Wilhelm II, which left the postwar federal republic to govern a devastated populace. The Treaty of Versailles imposed postwar reparation costs of 132 billion gold marks (around US$269 billion or €240 billion in 2019, or roughly US$32 billion in 1921), as well as limiting the army to 100,000 men and disallowing conscription, armored vehicles, submarines, aircraft, and more than six battleships. The consequential economic devastation, later exacerbated by the Great Depression, and the humiliation and outrage experienced by the German population are considered leading factors in the rise of Adolf Hitler and Nazism.
The German Confederation had been created by an act of the Congress of Vienna on 8 June 1815 as a result of the Napoleonic Wars, after being alluded to in Article 6 of the 1814 Treaty of Paris.
The liberal Revolutions of 1848 were crushed after the relations between affluent educated liberals and the urban artisans broke down; Otto von Bismarck's pragmatic Realpolitik, which appealed to peasants as well as the aristocracy, took its place. Bismarck sought to extend Hohenzollern hegemony throughout the German states; to do so meant unification of the German states and the exclusion of Prussia's main German rival, Austria, from the subsequent German Empire. He envisioned a conservative, Prussian-dominated Germany. The Second Schleswig War against Denmark in 1864, the Austro-Prussian War in 1866, and the Franco-Prussian War in 1870–1871 sparked a growing pan-German ideal and contributed to the formation of the German state, with victory for the Kleindeutsche Lösung ("Lesser German solution").
The German Confederation ended as a result of the Austro-Prussian War of 1866 between the constituent Confederation entities of the Austrian Empire and its allies on one side and Prussia and its allies on the other. The war resulted in the partial replacement of the Confederation in 1867 by a North German Confederation, comprising the 22 states north of the Main. The patriotic fervor generated by the Franco-Prussian War of 1870 overwhelmed the remaining opposition to a unified Germany (aside from Austria) in the four states south of the Main, and during November 1870, they joined the North German Confederation by treaty.
On 10 December 1870, the North German Confederation Reichstag renamed the Confederation the "German Empire" and gave the title of German Emperor to William I, King of Prussia, as Bundespräsidium of the Confederation. The new constitution (Constitution of the German Confederation) and the title Emperor came into effect on 1 January 1871. During the siege of Paris on 18 January 1871, William was proclaimed Emperor in the Hall of Mirrors at the Palace of Versailles.
The Constitution, adopted by the Reichstag on 14 April 1871 and proclaimed by the Emperor on 16 April, was substantially based upon Bismarck's North German Constitution. The political system remained the same. The empire had a parliament called the Reichstag, which was elected by universal male suffrage. However, the original constituencies drawn in 1871 were never redrawn to reflect the growth of urban areas. As a result, by the time of the great expansion of German cities in the 1890s and 1900s, rural areas were grossly overrepresented.
Legislation also required the consent of the Bundesrat, the federal council of deputies from the 25 states. Executive power was vested in the emperor (Kaiser), who was assisted by a chancellor responsible only to him. The emperor was given extensive powers by the constitution. He alone appointed and dismissed the chancellor, was supreme commander-in-chief of the armed forces, and final arbiter of all foreign affairs, and could also disband the Reichstag to call for new elections. Officially, the chancellor was a one-man cabinet and was responsible for the conduct of all state affairs; in practice, the State Secretaries (top bureaucratic officials in charge of such fields as finance, war, foreign affairs, etc.) functioned much like ministers in other monarchies. The Reichstag had the power to pass, amend, or reject bills and to initiate legislation. However, as mentioned above, in practice, the real power was vested in the emperor, who exercised it through his chancellor.