The German Empire (German: Deutsches Kaiserreich) is the common name given to the state officially named the Deutsches Reich (literally: "German Realm"), designating Germany from the unification of Germany and proclamation of Wilhelm I as German Emperor on 18 January 1871, to 1918, when it became a federal republic after defeat in World War I and the abdication of the Emperor, Wilhelm II.

The German Empire consisted of 27 constituent territories (most of them ruled by royal families). While the Kingdom of Prussia contained most of the population and most of the territory of the Reich; the Prussian leadership became supplanted by German leaders and Prussia itself played a lesser role. As Dwyer (2005) points out, Prussia's "political and cultural influence had diminished considerably" by the 1890s. Its three largest neighbors were rivals Imperial Russia to the east and France to the west and ally Austria-Hungary to the south.

After 1850, Germany industrialized rapidly, with a foundation in coal, iron (and later steel), chemicals and railways. From a population of 41 million people in 1871, it grew to 68 million in 1913. From a heavily rural nation in 1815, it was now predominantly urban. During its 47 years of existence, the German Empire operated as an industrial, technological and scientific giant, receiving more Nobel Prizes in science than Britain, France, Russia and the United States combined.

World War I (WWI), which was predominantly called the World War or the Great War from its occurrence until 1939 (World War II), and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918. It involved all the world's great powers, which were assembled in two opposing alliances: the Allies (based on the Triple Entente of the United Kingdom, France and Russia) and the Central Powers (originally centred around the Triple Alliance of Germany, Austria-Hungary and Italy; but, as Austria–Hungary had taken the offensive against the agreement, Italy did not enter into the war). These alliances both reorganised (Italy fought for the Allies), and expanded as more nations entered the war. Ultimately more than 70 million military personnel, including 60 million Europeans, were mobilised in one of the largest wars in history. More than 9 million combatants were killed, largely because of enormous increases in lethality of weapons, thanks to new technology, without corresponding improvements in protection or mobility. It was the sixth-deadliest conflict in world history, subsequently paving the way for various political changes such as revolutions in the nations involved.

Frederick II (German: Friedrich II.; 24 January 1712 – 17 August 1786) was a King in Prussia (1740–1772) and a King of Prussia (1772–1786) from the Hohenzollern dynasty. In his role as a prince-elector of the Holy Roman Empire, he was also Elector of Brandenburg. He was in personal union the sovereign prince of the Principality of Neuchâtel. He became known as Frederick the Great (Friedrich der Große) and was named Der Alte Fritz ("Old Fritz").

Interested primarily in music and philosophy and not the arts of war during his youth, Frederick unsuccessfully attempted to flee from his authoritarian father, Frederick William I, with childhood friend Hans Hermann von Katte, whose execution he was forced to watch after they were captured. Upon ascending to the Prussian throne, he attacked Austria and claimed Silesia during the Silesian Wars, winning military acclaim for himself and Prussia. Near the end of his life, Frederick physically connected most of his realm by conquering Polish territories in the First Partition of Poland.