Saxe-Weimar-Eisenach in the context of "German Revolution of 1918–19"

A grand duchy is a country or territory whose official head of state or ruler is a monarch bearing the title of grand duke or grand duchess.

Prior to the early 1800s, the only Grand duchy in Europe was located in what is now Italy: Tuscany (declared in 1569). During the 19th century there were as many as 14 grand duchies in Europe at once, some of which were revived after the Napoleonic Empire. Some of these were sovereign and nominally independent (Baden, Hesse and by Rhine, Mecklenburg-Schwerin, Mecklenburg-Strelitz, Oldenburg, Saxe-Weimar-Eisenach and Tuscany), some sovereign but held in personal union with larger realms by a monarch whose grand-dukedom was borne as a subsidiary title (Finland, Luxembourg, Transylvania), some of which were client states of a more powerful realm (Cleves and Berg), and some whose territorial boundaries were nominal and the position purely titular (Frankfurt).

Grand duke (feminine: grand duchess) is a European hereditary title, used either by certain monarchs or by members of certain monarchs' families. The title is used in some current and former independent monarchies in Europe, particularly:

• in present-day Luxembourg, the last surviving Grand Duchy
• historically by the sovereigns of former independent countries, such as Tuscany (from 1569 to 1860, now part of Italy)
• in Baden, Hesse, Oldenburg, Mecklenburg-Schwerin, Mecklenburg-Strelitz and Saxe-Weimar-Eisenach (officially simply the Grand Duchy of Saxony) – grand duchies from 1815 to 1918, and all now part of Germany
• formerly also in some countries in Northern Europe, such as the Grand Duchy of Finland or the Grand Duchy of Lithuania
• currently by claimants to the Russian Imperial Throne (eg. Grand Duke George Mikhailovich of Russia)

The Thuringian states (German: Thüringische Staaten) refers to the following eight German federal states within the German Empire:

• The Grand Duchy of Saxe-Weimar-Eisenach, officially the Grand Duchy of Saxony (Großherzogtum Sachsen) from 1903
• The duchies of Saxe-Altenburg, Saxe-Coburg and Gotha and Saxe-Meiningen (Herzogtum Sachsen-Altenburg, Herzogtum Sachsen-Coburg und Gotha, Herzogtum Sachsen-Meiningen)
• The principalities of Reuss Elder Line (Fürstentum Reuß Ältere Linie), Reuss Younger Line (Fürstentum Reuß Jüngere Linie), Schwarzburg-Rudolstadt (Fürstentum Schwarzburg-Rudolstadt) and Schwarzburg-Sondershausen (Fürstentum Schwarzburg-Sondershausen)