Duncker was born in Berlin,
Province of Brandenburg, as the eldest son of the publisher
Karl Duncker. He studied at the universities of
Bonn and
Berlin till 1834, was then accused of participation in the students' societies, which the government was endeavouring to suppress, and was condemned to six years' imprisonment, afterwards reduced to six months. He had already begun his labours as a historian, but after serving his sentence in 1837, found himself debarred till 1839 from completing his course at
Halle, where in 1842 he obtained a professorship. Elected to the
Frankfurt Parliament in 1848, he joined the Right Centre Party, and was chosen reporter of the projected constitution. He sat in the
Erfurt assembly in 1850, and in the
second Prussian chamber from 1849 to 1852. During the
crisis in Schleswig and Holstein in 1850 he endeavoured in person to aid the duchies in their struggles. An outspoken opponent of the policy of
Manteuffel, he was refused promotion by the Prussian government, and in 1857 accepted the professorship of history at
Tübingen. In 1859, however, he was recalled to Berlin as assistant in the ministry of state in the cabinet of
Charles Anthony, Prince of Hohenzollern. At that time,
Rudolf von Auerswald, a minister without portfolio, led the government in all but name. In 1861 was appointed councillor to the crown prince. In 1867 he became director of the Prussian archives, with which it was his task to incorporate those of
Hanover,
Hesse and
Nassau. He retired on 1 January 1875, and died at
Ansbach. ==Legacy==