Flag of Prussia

The state of Prussia had its origins in the separate lands of the Margraviate of Brandenburg and of the Duchy of Prussia. The Margraviate of Brandenburg developed from the medieval Northern March of the Holy Roman Empire, passing to the House of Hohenzollern in 1415. The Duchy of Prussia originated in 1525 when Albert of Brandenburg-Ansbach, a member of a cadet branch of the Hohenzollerns, secularized the eastern lands of the Teutonic Knights as a Polish fief. Prince-elector John Sigismund, Elector of Brandenburg, inherited the Duchy of Prussia in 1618, thus uniting Brandenburg and Prussia under one ruler in a personal union; the Elector's state became known as Brandenburg-Prussia. The Kingdom of Prussia formed when Elector Frederick III assumed the title of Frederick I, King in Prussia, on 18 January 1701.

Hohenzollern monarchical rule of Prussia ceased in 1918 after the fall of the German Empire in the aftermath of World War I; the Kingdom becoming instead the Free State of Prussia. The Allied Control Council decreed the formal abolition of the state of Prussia in 1947 following World War II.

The Prussian national and merchant flag was originally a simple black-white-black flag issued on May 22, 1818, but this was replaced on March 12, 1823 with a new flag. The revised one (3:5) was parted black, white, and black (1:4:1), showing in the white stripe the eagle with a blue orb bound in gold and a scepter ending in another eagle. On its breast were the intertwined initials FR for Fridericus Rex. The axis of the eagle is at 2/5 of the flag's total length.

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