When was the modern German flag designed?
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 relations deteriorating between the Soviet Union and the United States, the three western Allies met in March 1948 to merge their zones of occupation and allow the formation of what became the Federal Republic of Germany, commonly known as West Germany. Meanwhile, the eastern Soviet zone became the German Democratic Republic, commonly known as East Germany.
During the preparation of the new constitution for West Germany, discussions regarding its national symbols took place in August 1948 during a meeting at Herrenchiemsee. Although there were objections to the creation of a national flag before reunification with the east, it was decided to proceed. This decision was primarily motivated by the proposed constitution by the eastern SED in November 1946, where black-red-gold were suggested as the colours for a future German republic.