The concept of Germany as a distinct region in central Europe can be traced to Roman commander Julius Caesar, who referred to the unconquered area east of the Rhine as Germania, thus distinguishing it from Gaul (France), which he had conquered. The victory of the Germanic tribes in the Battle of the Teutoburg Forest (AD 9) prevented annexation by the Roman Empire, although the Roman provinces of Germania Superior and Germania Inferior were established along the Rhine. Following the Fall of the Western Roman Empire, the Franks conquered the other West Germanic tribes. When the Frankish Empire was divided among Charlemagne's heirs in 843, the eastern part became East Francia. In 962, Otto I became the first emperor of the Holy Roman Empire, the medieval German state.

In the High Middle Ages, the regional dukes, princes and bishops gained power at the expense of the emperors. Martin Luther led the Protestant Reformationagainst the Catholic Church after 1517, as the northern states became Protestant, while the southern states remained Catholic. The two parts of the Holy Roman Empire clashed in the Thirty Years' War (1618–1648), which was ruinous to the twenty million civilians. 1648 marked the effective end of the Holy Roman Empire and the beginning of the modern nation-state system, with Germany divided into numerous independent states, such as Prussia, Bavaria and Saxony.

After the French Revolution and the Napoleonic Wars (1803–1815), feudalism fell away and liberalism and nationalism clashed with reaction. The 1848 March Revolution failed. The Industrial Revolution modernized the German economy, led to the rapid growth of cities and to the emergence of the Socialist movement in Germany. Prussia, with its capital Berlin, grew in power. German universities became world-class centers for science and the humanities, while music and the arts flourished. Unification was achieved with the formation of the German Empire in 1871 under the leadership of Prussian Chancellor Otto von Bismarck. The new Reichstag, an elected parliament, had only a limited role in the imperial government. Germany joined the other powers in colonial expansion in Africa and the Pacific.

Germany was the dominant power on the continent. By 1900, its rapidly expanding industrial economy passed Britain's, allowing a naval race and an aggressive foreign policy. Germany led the Central Powers in World War I (1914–1918) against France, Great Britain, Russia and (by 1917) the United States. Defeated and partly occupied, Germany was forced to pay war reparations by the Treaty of Versailles and was stripped of its colonies as well as Polish areas and Alsace-Lorraine. The German Revolution of 1918–19 deposed the emperor and the various kings and princes, leading to the establishment of the Weimar Republic, an unstable parliamentary democracy.

In the early 1930s, the worldwide Great Depression hit Germany hard, as unemployment soared and people lost confidence in the government. In 1933, the Nazis under Adolf Hitler came to power and established a totalitarian regime. Political opponents were killed or imprisoned. Nazi Germany's aggressive foreign policy took control of Austria and parts of Czechoslovakia, and its invasion of Polandinitiated the Second World War. After forming a pact with the Soviet Union in 1939, Hitler and Stalin divided Eastern Europe. After a "Phoney War" in spring 1940 the German blitzkrieg swept Scandinavia, the Low Countries and France, giving Germany control of nearly all of Western Europe. Only the British Commonwealth and Empire stood opposed, along with Greece. Hitler invaded the Soviet Union in June 1941. In Germany, but predominantly in the German-occupied areas, the systematic genocide program known as The Holocaust killed six million Jews, as well as five million Poles, Romanies, Russians, Soviets (Russian and non-Russian), and others. In 1942, the German invasion of the Soviet Union faltered, and after the United States had entered the war, Britain became the base for massive Anglo-American bombings of German cities. Germany fought the war on multiple fronts through 1942–1944, however following the Allied invasion of Normandy (June 1944), the German army was pushed back on all fronts until the final collapse in May 1945.

Under occupation by the Allies, German territories were split up, denazification took place, and the Cold War resulted in the division of the country into democratic West Germany and communist East Germany. Millions of ethnic Germans fled from Communist areas into West Germany, which experienced rapid economic expansion, and became the dominant economy in Western Europe. West Germany was rearmed in the 1950s under the auspices of NATO, but without access to nuclear weapons. The Franco-German friendship became the basis for the political integration of Western Europe in the European Union. In 1989, the Berlin Wall was destroyed, the Soviet Union collapsed and East Germany was reunited with West Germany in 1990. In 1998–1999, Germany was one of the founding countries of the eurozone. Germany remains one of the economic powerhouses of Europe, contributing about one quarter of the eurozone's annual gross domestic product. In the early 2010s, Germany played a critical role in trying to resolve the escalating euro crisis, especially with regard to Greece and other Southern European nations. In the middle of the decade, the country faced the European migrant crisis, as the main receiver of asylum seekers from Syria and other troubled regions.