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 Austria
According to legend, the flag was invented by Duke Leopold V of Austria as a consequence of his fighting during the Siege of Acre. After a fierce battle, his white surcoat was completely drenched in blood. When he removed his belt, the cloth beneath remained unstained, revealing the combination of red-white-red. So taken was he by this singular sight that he adopted the colors and scheme as his banner. The incident was documented as early as 1260, though it is highly unlikely.