Flag of Germany
When Heinrich XI, Prince Reuss of Greiz was appointed by Joseph II, Holy Roman Emperor to rule the then-new Principality of Reuss-Greiz on 12 May 1778, the flag adopted by the "Fürstentum Reuß-Greiz" was the first-ever appearance of the black-red-gold tricolour in its modern arrangement in any sovereign state within what today comprises Germany – the Reuss elder line that ruled the principality used a flag whose proportions were close to a "nearly square"-shape 4:5 hoist/fly ratio, instead of the modern German flag's 3:5 figure.
Flag of Germany
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 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.