The Prussian national and merchant flag was originally a simple black-white-black flag issued on May 22, 1818, but this was replaced on March 12, 1823, with a new flag. The revised one (3:5) was parted black, white, and black (1:4:1), showing in the white stripe the eagle with a blue orb bound in gold and a scepter ending in another eagle. On its breast were the intertwined initials FR for Fridericus Rex. The axis of the eagle is at two-fifths of the flag's total length.
The Prussian war flag (3:5), adopted November 28, 1816, was originally swallow-tailed for one-fifth of the total length; the tail was later abandoned. At two fifths it showed the Prussian eagle (two-thirds of the flag's height). In the canton, the Iron Cross was placed (one-third of the flag's height).[1]
The royal standard of Prussia showed the Iron Cross charged with the shield and crown of the small state arms surrounded by the collar of the Order of the Black Eagle. On the blades of the cross is the motto Gott mit uns. Between the arms were Prussian eagles along the edges and a royal crown in carré with them, all on a purple or red background.
After the German Revolution of 1918–19, the Prussian state was slow to adapt its heraldry to republican forms. Only July 11, 1921, new arms were decreed by the Prussian prime minister. The 'gothic' eagle made way for the more natural-looking flying one and lost all its garments.
On December 16, 1921, the Ministry of State decreed that the Prussian flag was to be only black and white.
On February 24 and April 23, 1922, the ministry issued a service flag similar to the national flag of the 19th century – black borders above and below, being one-sixth of the total height of the flag, with the new eagle.[2]