Rank flag or distinguishing flag of the Austro-Hungarian Navy (K.u.k. Navy) 1786 to 1918, here Grossadmiral  around the year 1853. This flag was never used in this function, but was used as Admiral's Command Flag from 1880 to 1918. (De jure to 1915).
Flags &amp; Arms of the Modern Era: Austrian Empire, 1828 - 1853
Sir Iain