The men-servants of the military wear a small black cockade on their hat, the Hanoverian badge. The Stuart cockade was white. At the battle of Sherra-Muir, in the reign of George I., the English soldiers wore a black rosette in their hats. In the song of Sherra-Muir the English soldiers are called “the red-coat lads wi' black cockades.” (French, cocarde; German, kokarde.)
In the British Army and Navy the cockade, since the Hanoverian accession, has been black. AUSTRIAN cockade is black and yellow. All sentry boxes and boundary posts are so painted. Ein schwarz-gelber was the nickname of an Austrian Imperialist in 1848.
BAVARIA, light blue and white are the royal colours.
BELGIUM, black, yellow, and red.
FRANCE (regal), the royal colour was white.
HANOVER, the cockade was black. Black enters into all the German cockades.
PRUSSIA, black and white are the royal colours.
RUSSIA, green and white are the royal colours.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Cockade from Fact Monster: