Proclamation of the republic in Germany in the context of "Douglas Haig, 1st Earl Haig"

The Weimar Republic was a historical period of the German state from 9 November 1918 to 23 March 1933, during which it was a constitutional republic for the first time in history. The state was officially named the German Reich; it is also referred to, and unofficially proclaimed itself, as the German Republic. The period's informal name is derived from the city of Weimar,where the republic's constituent assembly took place. In English, the republic was usually simply called "Germany", with "Weimar Republic" (a term introduced by Adolf Hitler in 1929) not commonly used until the 1930s. The Weimar Republic had a semi-presidential system.

At the end of the First World War (1914–1918), the German Empire was economically and militarily exhausted and sued the Allies for peace. Awareness of an imminent defeat sparked the German revolution, the abdication of Kaiser Wilhelm II, the collapse of the Empire and the proclamation of the Weimar Republic. Hostilities in the war formally ceased with the Armistice of 11 November 1918.

The German revolution of 1918–1919, also known as the November Revolution (German: Novemberrevolution), was an uprising started by workers and soldiers in the final days of World War I. It quickly and almost bloodlessly brought down the German Empire. In its more violent second stage, the supporters of a parliamentary republic were victorious over those who wanted a Soviet-style council republic. The defeat of the forces of the far left cleared the way for the establishment of the Weimar Republic. The key factors leading to the revolution were the extreme burdens suffered by the German people during the war, the economic and psychological impacts of the Empire's defeat, and the social tensions between the general populace and the aristocratic and bourgeois elite.

The revolution began in late October 1918 with a sailors' mutiny at Kiel. Within a week, workers' and soldiers' councils were in control of government and military institutions across most of the Reich. On 9 November, Germany was declared a republic. By the end of the month, all of the ruling monarchs, including Emperor Wilhelm II, had been forced to abdicate. On 10 November, the Council of the People's Deputies was formed by members of Germany's two main socialist parties. Under the de facto leadership of Friedrich Ebert of the moderate Majority Social Democratic Party (MSPD), the Council acted as a provisional government that held the powers of the emperor, chancellor and legislature. It kept most of the old imperial officer corps, administration and judiciary in place so that it could use their expertise to address the crises of the moment.

The abdication of Wilhelm II as German Emperor and King of Prussia was declared unilaterally by Chancellor Max von Baden at the height of the German revolution on 9 November 1918, two days before the end of World War I. It was formally affirmed by a written statement from Wilhelm on 28 November while he was in exile in Amerongen, the Netherlands. The abdication ended the House of Hohenzollern's 300-year rule over Prussia and 500-year rule over its predecessor state, Brandenburg. With the loss of the monarchical legitimacy that was embodied by the emperor, the rulers of the Empire's 22 monarchical states also relinquished their royal titles and domains.

Wilhelm's abdication was triggered by Germany's impending defeat in World War I. In an attempt to obtain better terms from the Allies, a number of changes were made in the government and the constitution to partially democratise the Empire. The political changes were not enough to satisfy US President Woodrow Wilson, who was leading the attempt to broker an armistice. When it became clear that he wanted Wilhelm to abdicate, both the military and the government began to make various plans to save the monarchy through a regency or some other means after Wilhelm stepped down. The outbreak of the German revolution in the first days of November 1918 increased the pressure on Wilhelm to abdicate, but he continued to refuse. In order to calm the volatile situation in Berlin, Chancellor Baden, without Wilhelm's knowledge or approval, announced on 9 November that the Emperor had abdicated. Later that afternoon, Germany was proclaimed a republic, and Wilhelm went into exile in the Netherlands the next day. His official abdication came on 28 November. The 500-year-old Hohenzollern dynasty ended quietly, with almost no violence or fanfare.

9 November has been the date of a series of events that are considered political turning points in recent German history, some of which also had international repercussions. In particular the anniversaries of the fall of the Berlin Wall in 1989, the beginning of the November pogroms in 1938 (German: Kristallnacht or Reichspogromnacht), the Munich Putsch in 1923 and the proclamation of the Republic in 1918 during the November Revolution in Berlin, when viewed together in their respective contexts and received in relation to one another, form contextually and ideologically contrasting and polarizing highlights of the historical-political examination of Germany's history, especially that of the 20th century.

After the end of the Second World War, various historians and journalists coined the expression Schicksalstag (lit. 'Day of Fate' in German) for this date, but it only became widespread after the events of autumn 1989.