Serene Highness

Additionally, the treatment was granted for some, but not all, princely yet non-reigning families of Bohemia, Hungary, Italy, Poland, Romania and Russia by emperors or popes.

[citation needed] The following titleholders or families are authorised by the Crown to use the style Serene Highness[1] (French: Altesse Sérénissime, Dutch: Doorluchtige Hoogheid) In the lodges of the Grand Orient of Belgium, the latter's Grandmaster is styled (fr) Sérénissime Grand Maître, (nl) Doorluchtige Grootmeester.

Those members of the royal family who were not children or grandchildren of a king, i.e., the princes du sang, were entitled to be addressed as "Most Serene Highness" (Son Altesse Sérénissime, abbreviated S.A.S.).

[3] The current, legal usage of the style in the German-speaking countries is confined to the Princely Family of Liechtenstein, the entirety of which bears the treatment.

This is usually translated into English as Serene Highness, however, it would be more literal to translate it as superior to, above, beyond or greater than illustrious, as it is an augmentation of Erlaucht ("Illustrious Highness"), which was accorded to immediate counts (Reichsgrafen) of the Holy Roman Empire and by mediatised counts of the German Confederation and the German Empire.

As from 1664, Emperor Leopold I vested all Imperial Princes with the title, it became so common that the Electors like the Archdukes of Austria began to use the superlative address Durchlauchtigst.

[6] The mediatised House of Thurn and Taxis, entitled to the Serene Highness treatment in the German Empire, has a non-dynastic cadet branch, the Dukes di Castel Duino, which obtained naturalization in Italy in 1923.

See #German-speaking lands From 1853 to 1855, the president of Mexico, Antonio Lopez de Santa Anna, enjoyed the official style of Most Serene Highness, a treatment unique in that country.

After 1886, great-grandchildren of Russian emperors in the male line were Prince[ss] of Russia, and were to be granted the treatment of Highness, and Prince[ss] of Russia with the style of Serene Highness if more distantly descended from an emperor, and born from an equal marriage (as opposed to morganatic marriage).

However, when translated into non-Slavic languages and used in reference to a member of the imperial Romanov family, it was usually rendered as Serene Highness.

Previous to this grant the style was sometimes used by the Catholic Monarch Isabella and Ferdinand as well as by other houses known anciently as illustrious or serene.

During World War I, King George V revoked recognition of the style Serene Highness, hitherto used by some relatives of the British Royal Family who used German princely titles but lived in Britain.