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.
Reichskriegsflagge
Because Prussia had emerged as the leading German state and the black-red-golden colour scheme was, at that time, associated with pan-Germanism (a Germany including Austria) and the revolution of 1848, the Prussian King and President of the North German Confederation, Wilhelm I, insisted on using new flags inspired by Prussia and without the traditional German colours. Therefore, the North German and eventually Imperial German flags prominently featured the Prussian colours (black and white) as well as symbols like the Prussian eagle and the Iron Cross. And while seafaring was the traditional domain of the Hanse in Germany, virtually all of the 19th century German coastline (including the North Sea coast) and naval power belonged to Prussia after the decisive victory in 1866.