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
The Holy Roman Empire (800/962 – 1806, known as the "Holy Roman Empire of the German Nation" after 1512) did not have a national flag, but black and gold were used as colours of the Holy Roman Emperor and featured in the imperial banner: a black eagle on a golden background. After the late 13th or early 14th century, the claws and beak of the eagle were coloured red. From the early 15th century, a double-headed eagle was used.