Duchy of Oldenburg
Herzogtum Oldenburg
Timeline: Principia Moderni III (Map Game)

OTL equivalent: Oldenburg, East Frisia, Osnabruck
PMIII Flag of Oldenburg No coa
Flag Coat of Arms
PMIII Location Oldenburg
Oldenburg in green
Capital Oldenburg
Largest city Oldenburg
Other cities Jever, Osnabruck
Language German, Frisian
Religion Roman Catholicism
Demonym Oldenburger
Government Semi-constitutional Monarchy
  legislature Landtag of Oldenburg
Duke disputed, power exercised by Regency Council
  Royal house: disputed
Established 1091
Currency Gelder
Organizations Holy Roman Empire

The Duchy of Oldenburg, commonly referred to as Oldenburg, is a state on the North Sea, situated in the North-West of the Holy Roman Empire. It is bordered by Hamburg to the East and South-West, the Netherlands to the West, Hesse to the South, and Bavaria to the North-East.  

The Duchy is made up of two sections: Oldenburg proper and Osnabruck. Osnabruck, formerly a Prince-Bishopric vassal of the County of Oldenburg, was annexed by the latter in 1766, thus forming the current Duchy.

Oldenburg possesses numerous overseas colonies: Neu Norderney on the Labrador coast, Neu Juist on the Northern tip of Newfound Land, the Thabascho Protectorate in Southern Borealia, and small outposts in Greenland and the North Atlantic islands.


List of Oldenburger Monarchs 

House of Oldenburg

  • Christian V (1342-1421) married a local noblewoman
    • Dietrich I (1398-r 1421-1458) married Princess Branca of Portugal
      • Frederick (1418-r 1458-1466) married a Frisian noblewoman
        • Christian VI (1442-r 1466-1514 ) married Lady Juliet Leinster of the House of York
          • Adelheid (1472-r 1514-1542) married Duke Frederich of Hamburg
            • Frederich II (1499-1567) Duke of Hamburg, excluded from Oldenburger succession.
            • Dietrich II (1502-r 1542-1567) Married Princess Jacqueline of Albion, ruled as co-monarch with her as Richard IV of Britannia.
              • Wilhelm (1540-r 1567-1618) Also William III of Britannia
                • Alfred (fl. 1592-r 1618-1680) Also Alfred of Britannia
                • Mary (fl. 1592)
              • Johannes (b. 1540)
      • Elise (b 1419)
      • Sigelinde (b 1420) married a nobleman
        • Conrad (b 1450) married Katharina of Hesse
          • Conrad (b 1472)
            • Sir Conrad (fl 1534-1553) Lord of Neu Norderney as Conrad I, 1540-death
              •  Lords of Neu Norderney: Conrad II-IV
                • Conrad (fl 1794-1795) Lord of Neu Norderney as Conrad V
                  • Conrad (1778-r 1797-1858) see below
                  • Richard (fl 1796) Lord of Neu Norderney
                    • Lords of Neu Norderney: Conrad VI, VII
                      • Conrad (fl 1902-1931) Lord of Neu Norderney as Conrad VIII, first independent Lord from 1902
                        • Conrad (fl 1953-1957) Lord of Neu Norderney as Conrad IX, abdicated in favour of his son after defeat in Second World War
                          • Conrad (r 1957-present) Lord of Neu Norderney as Conrad X
    • Louise (fl 1401-1467) married Landgrave Ludwig I of Hesse
      • Landgraves of Hesse

House of Habsburg-Brandenburg

  • Albert I (1596-1680) Also Albert II of Britannia, married Elizabeth of Essex
    • George (1630) - Also George of Britannia, married Caroline of Ansbach
      • Albert II (1670-1700) Also Albert III of Britannia
    • William (1633-1689)
    • Anne (1635-1700)
  • Otto I, Margrave of Brandenburg (1594-1653)
    • Frederick II (1640)


  • From 1700-1797, the Count-ship, and later Duke-ship, of Oldenburg was disputed by claimants from the House of Scoland and the House of Hamburg. During this period, the five-man Regency Council acted as the supreme power in Oldenburg. In 1797, Conrad, son of Lord Conrad V of Neu Norderney, direct descendant of  Lord Conrad I and a member of a cadet branch of the original House of Oldenburg, was crowned Duke, ending the Interregnum. 

House of Oldenburg-Neu Norderney

  •  Conrad (1778-r 1797-1858) First Duke of Oldenburg, Holy Roman Emperor from 1831, married Princess Marguerite of Bavaria (b 1774)
    • Dietrich III (1799-r 1858-1892)
      • Christian VII (r 1892-1907)
        • Wilhelm II (r 1907-1941)
          • Wilhelm III (r 1941-1953 abdicated) Last Duke of Oldenburg, reigned until surrendering after defeat in Second World War.
            • Pretenders to the throne of Oldenburg
        • Alberich (fl 1856-1857) King-Consort of the United German Kingdoms, married King Mary von Hamburg (1857) 
    • Franz (b 1801) 

Vassals and Colonies

Prince-Bishopric of Osnabruck

Prince-Bishopric of Osnabruck
Hochstift Osnabruck
Timeline: Principia Moderni III (Map Game)
Flag of the Bishopric of Osnabruck Wappen Bistum Osnabrück
Flag Coat of Arms
Capital Osnabruck
Largest city Osnabruck
Language German
Religion Sedevacantist Catholicism
Demonym Osnabrucker
Government Eccelesiastical Principality
  legislature Chapter of Osnabruck
Prince-Bishop Klemens
Established 1225
Annexation to Duchy of Oldenburg
  date 1766
Osnabruck is an eccelesiastical principality to the South of Oldenburg. The bishopric was founded in 1225 after a long period of gradual increase in the Bishop's power. In 1418, Count Christian V of Oldenburg began diplomatic moves to vassalise Osnabruck. By 1433, Oldenburgers had infriltrated most key positions in the administration of the bishopric. Two years later, the ageing bishop died, leaving Count Dietrich free to appoint his chosen successor: his distant cousin, Father Alberich von Oldenburg. The following year, 1456, Bishop Alberich declared the bishopric to be officially Sedevacantist. During the reign of Alberich and his successor Klemens, the episcopal administration took gradual steps to put the Bishopric increasingly under the direct control of the Church. 

Crown Colony of Neu Baltrum

The uninhabited Arctic island of Neu Baltrum was discovered in 1449 by Kestner, an Oldenburger captain of an OHG ship, after it ship had been blown wildly off course on the way to greenlandic whaling outpost of Dietrichdorf. Kestner claimed the island for Oldenburg, and Count Dietrich ratified the claim at the end of the year. In 1450, the now-Governor Kestner set sail with five families, eight sheep, eight pigs, three goats, seeds, and tools to colonise the island. The settlement they founded became known as Waldorf, named after the whales which are processed there every year by the OHG whaling fleet. As of 1470, the colony had a permanent population of about seven families, as well as ten soldiers and one priest. The majority were based in Waldorf, although two families lived in the tiny hamlet of Neudorf, whilst one family operated a farm in the central highlands. 
Crown Colony of New Baltrum
Kronkolonie von Neu Baltrum
Timeline: Principia Moderni III (Map Game)

OTL equivalent: Jan Mayen
Flag of Neu Baltrum No coa
Flag Coat of Arms
Neu Baltrum
Location of Crown Colony of New Baltrum
Capital Waldorf
Largest city Waldorf
Other cities Neudorf
  others Frisian
Religion Sedevacantist Catholicism
Government Colony
  Royal house: Oldenburg
Governor Kestner
Area 573 km2
Population approx 50 people
Established 1449
Annexation to Oldenburg

Crown Colony of Neu Borkum


The national economy of Oldenburg in the 1400s was based on three pillars: agriculture, trade, and banking.

Agriculture was conducted at a very localised level, with individual manors producing grains such as wheat and barley, which were then sold on to markets.

Trade, on the other hand, was performed on a grand scale for such a small country. After the Oldenburger Handelsabenteurer Gesellschaft (OHG) gained its comital charter in 1412, it set about essentially monopolising all of Oldenburg's trade. In addition to the charter-imposed monopoly over trade with Albion, the UNC and North Africa, the company was able to gain a virtual monopoly over trade with Venice and Hesse. In 1431, the company made the decision to start whaling, sealing and auking in the Arctic and North seas. With virtually no copetition in the area, the enterprise was extremely profitable, so much so that colonies on Neu Baltrum and Neu Borkum were financially viable for the comital government. Oldenburg's main export from 1431 onward then, was whale, seal, walrus and auk products derived from the North and Arctic seas and the coasts of the colonies. These goods were traded in the Mediteranean, German states and Albion for other goods, such as cloths, spices, and money.  

Banking truly began in Oldenburg in 1452, when Count Dietrich accepted the Venetian request for a branch of the Roscol Bank to be set up in Oldenburg. A mere four years later, a group of Oldenburger merchants and nobles joined with some jewish moneylenders to form the Jade Bank, Oldenburg's first native bank. It received comital recognition the following year, and quickly grew to rival the Roscol Bank. With mainly Jews operating the bank, it was able to circumvent Canon Law and engage in usury, thus enabling the bakn to give high-risk loans to farmers and fishermen. The significance of this to Oldenburg was twofold: firstly it enabled greater growth in the agricultural and fishing sectors, and secondly, it started a general pro-Jewish sentiment amongst the population -a rare sight in Mediaeval Germany. 

Foreign Affairs and Military

Foreign Affairs

A brief description of Oldenburg's relations with other countries:


  • Hesse: Oldenburg maintains friendly relations with Hesse. Two notable royal marriages took place in the 15th century, with Louise marryinh Landgrave Ludwig I of Hesse, and Prince Conrad marrying Katharina of Hesse. Good trading ties were strengthened in 1471 when the two nations established a joint trading post fort on the Ivory Coast.  
  • The Holy Roman Empire: Oldenburg is a member-state. 
  •  VeniceLa Serenissima is a strong trading partner, so much so that the Oldenburger Gulden is pegged to the Venetian Ducat. OHG ships travel annually to Venice itself to trade, and have been honoured with their own warehouse on the docks. As well as that, the Venetian-owned Roscol Bank is an integral part of the baking sector. 

Friendly but Neutral

  • Scandinavia: Oldenburg and Scandinavia have managed to live harmoniously with each other for many decades, with Scandinavia being so kind as to first lease and later sell Oldenburg a small Greenlandic island. 
  • Netherlands: Braibant-Holland, the predecessor to the Netherlands, cooperated with Oldenburg in the taking of Frisia. Relations cooled after the Dutch revolted out of the HRE, but have remained positive. 
  • Portugal: Count Dietrich the Good married Princess Branca of Portugal in the early 1400s, starting a good relationship with the Iberian state. The OHG also frequents Portugal on the way to and from the Mediteranean.
  • Albion: Albion is also a trading partner and a valuable market for the whaling products of the OHG. Ties were strengthened in 14__ with the marriage of Count Christian VI to Lady Juliet Leinster of York. 


  • In the 1400s, Oldenburg had no enemies. 


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