The Free State of Prussia was one of the constituent states of the Weimar Republic from 1918 to 1947. It was the successor to the Kingdom of Prussia after the defeat of the German Empire in World War I and the overthrow of the German monarchies in the revolution of 1918–1919. Even though most of Germany's post-war territorial losses in Europe had come from its territory, Prussia continued to be the dominant state in Germany during the Weimar Republic as it had been during the Empire. It was home to the federal capital Berlin and had roughly three-fifths of Germany's territory and population. Prussia changed from the authoritarian state it had been and became a parliamentary democracy under its 1920 constitution. During the Weimar period, it was governed almost entirely by pro-democratic parties and was more politically stable than the Republic itself. With only brief interruptions, the Social Democratic Party (SPD) provided the minister president.