Nazi Germany, or the Third Reich, is the common name for the country of Germany while governed by Adolf Hitler and his National Socialist German Workers' Party (NSDAP) from 1933 to 1945. Third Reich (German: Drittes Reich) denotes the Nazi state as a historical successor to the medieval Holy Roman Empire (962–1806) and to the modern German Empire (1871–1918). Nazi Germany had two official names, the Deutsches Reich (German Reich), from 1933 to 1943, when it became Großdeutsches Reich (Greater German Reich).

On 30 January 1933, Adolf Hitler was appointed Chancellor of Germany. Although he initially headed a coalition government, he quickly eliminated his government partners. At this time the German national borders still were those established in the peace Treaty of Versailles (1919), between Germany and the Allied Powers (United Kingdom, France, the United States, Italy, Japan et alii.) at the end of the First World War (1914–18); to the north, Germany was bounded by the North Sea, Denmark, and the Baltic Sea; to the east, it was divided into two and bordered Lithuania, the Free City of Danzig, Poland, and Czechoslovakia; to the south, it bordered Austria and Switzerland, and to the west, it touched France, Luxembourg, Belgium, the Netherlands, the Rhineland, and the Saarland. These borders changed after Germany regained control of the Rhineland, Saarland and the Memelland and annexed Austria, the Sudetenland and Bohemia and Moravia. Germany expanded into Greater Germany during the Second World War, which began in 1939 after Germany invaded Poland, triggering the United Kingdom and France to declare war on Germany.

During the war, Germany conquered and occupied most of Europe and Northern Africa. The Nazis persecuted and murdered millions of Jews and other minorities in the Holocaust Final Solution. Despite its Axis alliance with other nations, mainly Italy and Japan, by 1945 Germany had been defeated, and was occupied by four of the Allied powers (France, Soviet Union, UK and US).

Nazi Germany arose in the wake of the national shame, embarrassment, anger, and resentment resulting from the Treaty of Versailles (1919), that dictated, to the vanquished Germans, responsibility for:

Other conditions fostering the rise of the Third Reich include nationalism and Pan-Germanism, civil unrest attributed to Marxist groups, the global Great Depression of the 1930s (consequent to the Wall Street Crash of 1929), hyperinflation, the reaction against the counter-traditionalism and liberalism of the Weimar Republic, and the rise of communism in Germany, i.e. the growth of the KPD (Communist Party of Germany). Many voters, seeking an outlet for their frustrations, and an expression for their repudiation of parliamentary democracy, which appeared incapable of keeping a government in power for more than a few months, began supporting far right-wing and far left-wing political parties, opting for political extremists such as the Nazi Party, (Nationalsozialistische Deutsche Arbeiterpartei, NSDAP, National Socialist German Workers' Party)

The Nazis promised strong, authoritarian government in lieu of effete parliamentary republicanism, civil peace, radical economic policy (including full employment), restored national pride (principally by repudiating the Versailles Treaty), and racial cleansing, partly implemented via the active suppression of Jews and Marxists, all in name of national unity and solidarity, rather than the partisan divisions of democracy, and the social class divisiveness of Marxism. The Nazis promised national and cultural renewal based upon Völkisch movement traditionalism, and proposed rearmament, repudiation of reparations, and reclamation of territory lost to the Treaty of Versailles.

The Nazi Party claimed that through the Treaty, the Weimar Republic’s liberal democracy, the traitorous “November criminals” had surrendered Germany's national pride, by the inspiration and conniving of the Jews, whose goal was national subversion and the poisoning of the German blood. To establish that interpretation of recent German history, the Nazi propaganda effectively used the Dolchstoßlegende (“Dagger-stab in the Back Legend”) explaining the German military failure.

From 1925 to the 1930s, the German government evolved from a democracy to a de facto conservative–nationalist authoritarian state under war hero-President Paul von Hindenburg, who disliked the liberal democracy of the Weimar Republic, and wanted to make Germany into an authoritarian state. The natural ally for establishing authoritarianism was the German National People's Party (Deutschnationale Volkspartei, DNVP), "the Nationalists", but, after 1929, with the German economy floundering, more radical and younger nationalists were attracted to the revolutionary nature of the National Socialist Party, to challenge the rising popular support for communism. Moreover, the middle-class political parties lost support as the voters aggregated to the left- and right- wings of the German political spectrum, thus making majority government, in a parliamentary system, even more difficult.

In the federal election of 1928, when the economy had improved after the hyperinflation of the 1922–23 period, the Nazis won only 12 seats. Two years later, in the federal election of 1930, months after the US stock market crash, the Nazi Party won 107 seats, progressing from ninth-rated splinter group to second-largest parliamentary party in the Reichstag. After the federal election of 1932, the Nazis were the largest party in the Reichstag, holding 230 seats. President Hindenburg was reluctant to confer substantial executive power to Adolf Hitler, but former chancellor Franz von Papen and Hitler concorded an NSDAP–DNVP party alliance that would allow Hitler’s chancellorship, subject to traditional-conservative control, for President Hindenburg to develop an authoritarian state. In the event, Hitler consistently demanded to be appointed chancellor, in exchange for Hindenburg’s receiving any Nazi Party support of the cabinets appointed under his authority.

On 30 January 1933, President Paul von Hindenburg appointed Adolf Hitler as Chancellor of Germany, after General Kurt von Schleicher’s failure to form a viable government (see Machtergreifung). Hitler pressured Hindenburg through his son Oskar von Hindenburg, and via intrigue by former Chancellor Franz von Papen, former leader of the Catholic Centre Party.[citation needed] By becoming the Vice Chancellor and keeping the Nazis a cabinet minority, von Papen expected to be able to control Hitler. Although the Nazis had won the greatest share of the popular vote in the two Reichstag general elections of 1932, they had no majority of their own, not even with the NSDAP–DNVP alliance that started governing in 1933 by Presidential Decree, per Article 48 of the 1919 Weimar Constitution.