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
With the end of the Holy Roman Empire in 1806, many of its dukes and princes joined the Confederation of the Rhine, a confederation of Napoleonic client states. These states preferred to use their own flags. The confederation had no flag of its own; instead it used the blue-white-red flag of France and the Imperial Standard of its protector, Napoleon.