Alexander Duncker

Another brother, Hermann Carl Rudolf Duncker (1817–1892) was a member of the Prussian National Assembly and a mayor of Berlin.

He was instrumental in promoting new authors, and some of them Emanuel Geibel, Wilhelm Jensen, Marie Petersen, Gustav zu Putlitz, and Theodor Storm found their first recognition through Duncker's efforts.

As a reserve officer attaining the rank of lieutenant colonel, he participated in the wars against Denmark (1864), Austria (1866), and France (1870-71).

A high point in his output was a graphic collection of Prussian castles under the title, Die ländlichen Wohnsitze, Schlösser und Residenzen der ritterschaftlichen Grundbesitzer in der preussischen Monarchie nebst den königlichen Familien-, Haus-Fideicommiss- und Schatull-Gütern in naturgetreuen, künstlerisch ausgeführten, farbigen Darstellungen nebst begleitendem Text (in English: The rural residences, castles, and palaces of the knightly landowners in the Prussian monarchy, along with the royal families estates, fideicommissum estates, and private sovereign estates, depicted in lifelike, artistically executed, colorful illustrations with accompanying text) appearing from 1857 to 1883.

[1] The collection is especially valuable for its pictorial record of numerous stately buildings from the old eastern German lands, many of which were destroyed during and after World War II when these regions were transferred to Poland and the Soviet Union.