The Constitution of the German Empire () was the basic law of the German Empire of 1871-1918, from 16 April 1871, coming into effect on 4 May 1871. German historians often refer to it as Bismarck's imperial constitution, in German the Bismarcksche Reichsverfassung (BRV). According to the constitution, the empire was a federation (federally organised national state) of 25 German states under the permanent presidency of Prussia, the largest and most powerful state. The presidency of the confederation (Bundespräsidium) was a hereditary office of the King of Prussia, who had the title of German Emperor. The Emperor appointed the Chancellor, the head of government and chairman of the Bundesrat, the council of representatives of the German states. Laws were enacted by the Bundesrat and the Reichstag, the Imperial Diet elected by male Germans above the age of 25 years. The constitution followed an earlier constitution of 1 January 1871, the Constitution of the German Confederation. That constitution had already incorporated some of the agreements between the North German Confederation and the four German states south of the River Main. It renamed the country to Deutsches Reich (conventionally translated to 'German Empire') and gave the Prussian King the title of German Emperor. The constitutions of 1 January and 4 May 1871 are both essentially an amended version of the North German Constitution, which had likewise been instigated by Otto von Bismarck. The political system remained the same. The constitution lost its effect in the November Revolution of 1918: the legislative and executive powers were performed by a new revolutionary organ. A national assembly created in 1919 a new, republican constitution: the Weimar Constitution, which has the same title in German as its predecessor (Verfassung des Deutschen Reiches, or 'Constitution of the German Reich'). Signatories and members The constitution was signed by William I, the King of Prussia, acting in his capacity as Bundespräsidium of the North German Confederation, the Kings of Bavaria and Württemberg, and the Grand Dukes of Baden and Hesse. Hesse north of the river Main was already a member of the North German Confederation; its territory south of the river was now included as well. The member states of the North German Confederation that now became members of the Empire were Prussia, Saxony, Mecklenburg-Schwerin, Saxe-Weimar-Eisenach, Mecklenburg-Strelitz, Oldenburg, Brunswick, Saxe-Meiningen, Saxe-Altenburg, Saxe-Coburg-Gotha, Anhalt, Schwarzburg-Rudolstadt, Schwarzburg-Sondershausen, Waldeck, Reuss (older line), Reuss (younger line), Schaumburg-Lippe, Lippe, Lübeck, Bremen, and Hamburg. The