From 1868 onward, the principality was administered by Prussia, but retained its legislative sovereignty. Prussian administration served to reduce administrative costs for the small state and was based on a ten-year contract that was repeatedly renewed. In 1871 it became a constituent state of the new German Empire. At the end of World War I, during the German Revolution the prince abdicated and Waldeck–Pyrmont became a free state within the Weimar Republic. On 30 November 1921, following a local plebiscite, the town and district of Pyrmont were detached and incorporated into the Prussian Province of Hanover, with Waldeck following into the Prussian province of Hesse-Nassau in 1929.