Duke of Augustenborg

Duke of Augustenborg was a title conferred by the King of Denmark to the head of a certain younger branch of the House of Oldenburg (Danish, Oldenborg), the branch known in Danish as "Slesvig-Holsten-Sønderborg-Augustenborg", and in German as "Schleswig-Holstein-Sonderburg-Augustenburg".

History

The branch originated from Ernest Gunther, a member of the ducal House of Schleswig-Holstein (its branch of Sønderborg) and a cadet of the royal house of Denmark, the third son of Alexander (1573-1627), 2nd Duke of Sonderborg, thus a grandson of duke Hans (1545-1622), the 1st duke, who was a son of King Christian III.

Ernest Gunther had a castle built in the years after 1651, which received the name Augustenborg in honor of his wife, Auguste, herself also from a branch of Dukes of Schleswig-Holstein, daughter of Philip (1584-1663), Duke of Glucksburg. As that castle became the chief seat of their line, the line eventually used the name Augustenborg as its branch name. As they were agnates of the ducal house, the title of Duke belonged to everyone of them (as is the Germanic custom).

The Dukes of Augustenborg were not sovereign rulers — they held their lands in fief to the sovereign Dukes of Schleswig and Holstein - the Kings of Denmark.

Later, a Danish king made the head of that line specifically Duke of Augustenborg. In the late 18th century, since 1764, the branch of Slesvig-Holsten-Sønderborg-Augustenborg was genealogically the next senior immediately after the main line of Danish kings, and had much Danish nobility blood in their veins. King Frederick VI of Denmark, or rather his chief adviser Andreas Peter Bernstorff, made his only sister Louise Auguste of Denmark to marry the then Hereditary Prince of Augustenborg.

In 1764 Sønderborg castle, the seat of that elder Schleswig-Holstein branch, passed upon its extinction into the hands of the Duke of Augustenborg, but against expectations it did not became a residence (they remained at Augustenborg). Instead it was rented out as a warehouse. The penultimate Duke of Augustenborg, also named Ernst Günther, allowed Sønderborg County Museum to move into a part of the castle in 1920. The next year the Danish state bought the castle from the Duke.

In 1810, a younger scion of the family, Prince Christian August, was chosen as the Crown Prince of Sweden, and adopted by king Charles XIII of Sweden. The Augustenborg dynasty on a royal throne was however not to be actualized, as Prince Christian August died just in a couple of months after his arrival in Sweden.

In the early 19th century the Danish royal line started to go extinct. The Duke of Augustenborg was the next male-line heir to the royal house, though not descended in male line from Frederick III of Denmark and Norway. This made the duke a player in the convoluted Schleswig-Holstein Question, as well in the Danish succession. Frederik August of Augustenborg attempted to proclaim himself as Duke Frederick VIII of Schleswig-Holstein in 1864 upon the final extinction of the main branch, Danish kings.

His daughter Augusta Victoria of Schleswig-Holstein became German Empress as consort of Wilhelm II.

The ducal line died out in 1931. After its extinction, the senior status went to the line of Dukes of Glucksburg, heads of another line, the line known in German as "Schleswig-Holstein-Sonderburg-Glücksburg" and in Danish as Slesvig-Holsten-Sønderborg-Lyksborg.

Dukes of Schleswig-Holstein-Sønderborg-Augustenborg

*1647 - 1689 Ernst Günther
*1689 - 1692 Frederik, son
*1692 - 1731 Ernest August, brother
*1731 - 1754 Christian August, nephew
*1754 - 1794 Frederik Christian I, son
*1794 - 1814 Frederik Christian II, son
*1814 - 1869 Christian August, son.

His son had proclaimed himself Duke of Schleswig-Holstein in 1863, and later Dukes of the line used this higher title, then recognized by Prussia as equivalent of mediatized principalities.

Dukes of Schleswig-Holstein, 1863-1931

*1863 - 1880 Frederik August (Frederik VIII), son
*1880 - 1921 Ernest Günther, son
*1921 - 1931 Albert, cousin of previous.

On the death of Duke Albert the Augustenburg line became extinct,the sub-line agnatic Targino-Flensburg and sub-line of House of Holstein-Gottorp is pretender the head of the Royal House.

Like the previous Oldenburg dynasty all previous monarchs of the Glücksburg dynasty in Denmark also claimed the titles as Dukes of Schleswig and Holstein. The current Danish monarch, Queen Margrethe II abandoned this tradition upon ascending the Danish throne in 1972. The Glücksburg dynasty considered the two territories to be separate entities and it consequently never used titles using the form "Schleswig-Holstein". The Russian Romanov dynasty used the form "Schleswig-Holstein".