Following the dissolution of the German Confederation, Prussia formed its unofficial successor, the North German Confederation, in 1866 with the signing of the Confederation Treaty in August 1866 and then the ratification of the Constitution of 1867. This coalition consisted of Prussia, the largest member state, and 21 other north German states.
The question regarding what flag should be adopted by the new confederation was first raised by the shipping sector and its desire to have an internationally recognisable identity. Virtually all international shipping that belonged to the confederation originated from either Prussia or the three former Hanseatic city-states of Bremen, Hamburg, and Lübeck. Based on this, Adolf Soetbeer, secretary of the Hamburg Chamber of Commerce, suggested in the Bremer Handelsblatt on 22 September 1866 that any planned flag should combine the colours of Prussia (black and white) with the Hanseatic colours (red and white). In the following year, the constitution of the North German Confederation was enacted, where a horizontal black-white-red tricolour was declared to be both the civil and war ensign.
King Wilhelm I of Prussia was satisfied with the colour choice: the red and white were also taken to represent the Margraviate of Brandenburg, the Imperial elector state that was a predecessor of the Kingdom of Prussia. The absence of gold from the flag also made it clear that this German state did not include the "black and gold" monarchy of Austria. Following the Franco-Prussian War, the remaining southern German states allied with the North German Confederation, leading to the unification of Germany and the elevation of the Prussian monarch to Emperor of this new state in 1871. In its constitution, the German Empire retained black, white, and red as its national colours, with the tricolour previously used by the North German Confederation officially adopted as its flag in 1892.
The black-white-red tricolour remained the flag of Germany until the end of the German Empire in 1918, in the final days of World War I.
Most mass-produced flags are commonly 150x90cm / 5x3' or 90x60cm / 3x2', which will often vary from the official size ratio. We now offer a custom-manufactured official size option for our many of our flags.