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.
Imperial law regarding the introduction of a German war and civil ensign
The Imperial law regarding the introduction of a war and civil ensign (German: "Reichsgesetz betreffend die Einführung einer deutschen Kriegs- und Handelsflagge") was an imperial law of the revolutionary German Empire of 1848. It describes the colours black-red-gold and the usage of a general German imperial flag and a war ensign for the Imperial Fleet.