Grand duke

The title is used in some current and former independent monarchies in Europe, particularly: The term grand duke as a monarch reigning over an independent state was a later invention (in Western Europe at first in 1569 for the ruler of Tuscany) to denote either a particularly mighty duke or a monarchy playing an important political, military and/or economic role, but not large enough to be a kingdom.

One of the first examples occurred when Count Gonçalo I Mendes of Portucale (in northwest Portugal and considered as that country's original nucleus) took, in 987, the personal title of Magnus Dux Portucalensium ("Grand Duke of the Portuguese") and rebelled against his feudal lord, King Bermudo II of León.

He was defeated by the royal armies but nevertheless obtained a remarkable autonomy as a Magnus Dux (Grand Duke), leading ultimately to Portuguese independence from the Spanish kingdom of Castille-León.

They tried—ultimately without success—to create from these territories under their control a new unified country between the Kingdom of France in the west and the Holy Roman Empire (mainly present-day Germany) in the east.

The title magnus dux or grand duke (Kunigų kunigas, Didysis kunigaikštisin Lithuanian) has been used by the rulers of Lithuania, who after Jogaila also became kings of Poland.

From 1573, both the Latin version and its Polish equivalent wielki książę (literally "grand prince"), the monarchic title of the rulers of Lithuania as well as of (western) Russia, Prussia, Mazovia, Samogithia, Kiev, Volhynia, Podolia, Podlachia, Livonia, Smolensk, Severia and Chernigov (including hollow claims nurtured by ambition), were used as part of their full official monarchic titles by the Kings (Polish: król) of Poland during the Polish–Lithuanian Commonwealth.

[1] Napoleon I awarded the title extensively: during his era, several of his allies (and de facto vassals) were allowed to assume the title of grand duke, usually at the same time as their inherited fiefs (or fiefs granted by Napoleon) were enlarged by annexed territories previously belonging to enemies defeated on the battlefield.

In the German and Dutch languages, which have separate words for a prince as the issue (child) of a monarch (respectively Prinz, Prins) and for a sovereign prince (Fürst, Vorst), there is also a clear linguistic difference between a sovereign grand duke reigning over a state of central and western Europe (Großherzog, Groothertog) and a non-sovereign, purely ceremonial grand duke of either the Russian imperial family or other non-sovereign territories that are de facto dependencies of a major power (Großfürst, Grootvorst).

The title of "Grand Duke" (megas doux) was created by Alexios I Komnenos and was conferred upon the commanding admiral of the Byzantine navy.

This system didn’t last very long, and in 12th century multiple northern princes of the Rurikid Dynasty could compete for their dominance in Kiev.

Grand Prince Ivan IV of Muscovy was the last monarch to reign without claiming any higher title, until he finally assumed the style Tsar of Russia in 1547.

Junior members of the family also generally bore the lower title of prince or princess with the style of "Grand Ducal Highness".

However, in other grand duchies (e.g., Oldenburg), junior members of the family bore the title of duke or duchess, with the style of "Highness" (HH).