Nazi Germany[h] (officially known as the German Reich[i] 1933–43, later the Greater German Reich[j] 1943–45) was the German state between 1933 and 1945, when Adolf Hitler and the Nazi Party controlled the country, transforming it into a dictatorship.

Under Hitler's rule, Germany quickly became a totalitarian state where many aspects of life were controlled by the government. The Third Reich,[k] meaning "Third Realm" or "Third Empire", referred to the Nazi claim that Nazi Germany was the successor to the earlier Holy Roman Empire (800–1806) and German Empire (1871–1918). The Third Reich, which the Nazis referred to as the Thousand-Year Reich,[l] ended in May 1945, after only 12 years, when the Allies defeated Germany and entered the capital, Berlin, ending World War II in Europe.

The Nazi Party became the largest in parliament following the July 1932 German federal election, but it did not hold a majority. Hitler refused to participate in a coalition government unless he was its leader. By the constitution of the Weimar Republic, in those circumstances the chancellor of Germany (the head of government) could be appointed by the president, Paul von Hindenburg, who appointed Hitler on 30 January 1933, on behest of right-wing politicians and industrialists. The Reichstag fire was used to pass the Reichstag Fire Decree, leading to the suppression of civil liberties and mass arrests of political opponents. The Enabling Act of 1933 gave Hitler's government the power to make and enforce laws without the Reichstag (parliament) or president. The Nazis began to eliminate political opposition and consolidate power. Hindenburg died in August 1934, and Hitler became dictator by merging the powers of the chancellery and presidency. A 1934 German referendum confirmed Hitler as sole Führer (leader). Power was centralised in Hitler's person, his word became the highest law. The government was not a coordinated, co-operating body, but a collection of factions struggling for power and Hitler's favour. In the midst of the Great Depression, the Nazis restored economic stability and ended mass unemployment, using heavy military spending. Financed by deficit spending, the regime undertook extensive public works projects, including the Autobahnen (motorways) and a massive secret rearmament program, forming the Wehrmacht (armed forces). The return to economic stability boosted the regime's popularity.

Racism, Nazi eugenics, and especially antisemitism were central ideological features of the regime. The Germanic peoples were considered by the Nazis to be the "master race", the purest branch of the Aryan race. Discrimination and persecution of Jews and Romani people accelerated. The first concentration camps were established in March 1933. Jews, liberals, socialists, communists, other political opponents and undesirables were imprisoned, exiled, or murdered. Christian churches and citizens that opposed Hitler's rule were oppressed and leaders imprisoned. Education focused on racial biology, population policy, and fitness for military service. Career and educational opportunities for women were curtailed. The 1936 Summer Olympics showcased Germany on the international stage. Propaganda Minister Joseph Goebbels made effective use of film, mass rallies, and Hitler's hypnotic oratory to influence public opinion. The government controlled artistic expression, promoting specific art forms and banning or discouraging others.

From the latter half of the 1930s, Nazi Germany made increasingly aggressive territorial demands, threatening war if these were not met. The Saarland voted to rejoin Germany in 1935, and in 1936 Hitler sent troops into the Rhineland, which had been demilitarized after World War I. Germany seized Austria in the Anschluss of 1938, and demanded and received the Sudetenland region of Czechoslovakia in that same year. In March 1939, the Slovak state was proclaimed and became a client state and the German Protectorate of Bohemia and Moravia was established on the remainder of occupied Czech lands. Germany signed a non-aggression pact with the Soviet Union and invaded Poland on 1 September 1939, launching World War II in Europe. By late 1942, Germany and its European allies in the Axis powers controlled much of Europe and North Africa. Germany exploited the raw materials and labour of its occupied territories and allies.

Genocide, mass murder, and large-scale forced labour became hallmarks of the regime. Hundreds of thousands with mental or physical disabilities were murdered in hospitals and asylums. Einsatzgruppen paramilitary death squads accompanied the armed forces inside the occupied territories and conducted genocide of millions of Jews and other Holocaust victims. Millions were imprisoned, worked to death, or murdered in Nazi concentration camps and extermination camps. This genocide is known as the Holocaust.

While the German invasion of the Soviet Union in 1941 was initially successful, the Soviet resurgence and entry of the US into the war meant Germany lost the initiative in 1943, and by late 1944 had been pushed back to the 1939 border. Large-scale aerial bombing of Germany escalated and the Axis powers were driven back in Eastern and Southern Europe. After the Allied invasion of France, Germany was conquered by the Soviet Union from the east and the other Allies from the west, and capitulated on 8 May 1945. Hitler's refusal to admit defeat led to massive destruction of German infrastructure and additional war-related deaths in the closing months of the war. The Allies initiated a policy of denazification and put many of the surviving Nazi leadership on trial for war crimes at the Nuremberg trials.