William I, Elector of Hesse

William I, Elector of Hesse (German: Wilhelm I., Kurfürst von Hessen; 3 June 1743 – 27 February 1821) was the eldest surviving son of Frederick II, Landgrave of Hesse-Kassel (or Hesse-Cassel) and Princess Mary of Great Britain, the daughter of George II.

William I
Elector of Hesse
Wilhelm IX. Landgraf von Hessel-Kassel Boettner.jpg
Portrait by Wilhelm Böttner, c. 1795
Landgrave of Hesse-Kassel
Reign31 October 1785 –
27 February 1821
PredecessorFrederick II
SuccessorWilliam II
Born(1743-06-03)3 June 1743
Kassel, Hesse-Kassel, Holy Roman Empire
Died27 February 1821(1821-02-27) (aged 77)
Kassel, Hesse, German Confederation
(m. 1764; died 1820)
among others...
FatherFrederick II, Landgrave of Hesse-Kassel
MotherPrincess Mary of Great Britain


Early lifeEdit

Prince William as a boy.

Prince William was born on 3 June 1743 in Kassel, capital of the Landgraviate of Hesse-Kassel in the Holy Roman Empire. Born into the House of Hesse, he was the second but eldest surviving son of Prins Frederick of Hesse-Kassel (the future Landgrave Frederick II), and his wife Princess Mary of Great Britain. A former heir to the landgraviate, also named William, had died in infancy in 1742; therefore, hopes were high for the future of the new heir apparent. He had two younger brothers: Prince Charles and Prince Frederick.

His father's marriage with the British princess was not a happy one, and Frederick abandoned the family in 1747 and converted to Catholicism in 1749. In 1755 he formally annulled his marriage. William's grandfather, Landgrave William, granted the newly acquired principality of Hanau to his daughter-in-law and grandsons. Technically, young William became the reigning prince of Hanau, while under his mother's regency. The young prince William, together with his two younger brothers, lived with their mother, the landgravine Mary. From 1747 they were supported by Protestant relatives and moved to Denmark. There they lived with Mary's sister, Louise of Great Britain, and her family; Louise died in 1751.


On 1 September 1764, William married his first cousin, Wilhelmina Caroline of Denmark and Norway (1747–1820), who was the second surviving daughter of Frederick V of Denmark and Norway. They married at Christiansborg Palace and resided for two decades mostly in Denmark.

In 1785 they moved to Kassel when William succeeded to the landgraviate. During the lifetime of his father, William had already received the Principality of Hanau, south of the Hessian territories near Frankfurt, as successor of its newly extinct princes. The Hanau people did not want to have a Catholic ruler.

William's younger brother Charles in 1766 married another of their Danish first cousins, Princess Louise of Denmark.


Upon the death of his father on 31 October 1785, he became William IX, Landgrave of Hesse-Kassel. He was said to have inherited one of the largest fortunes in Europe at the time.[citation needed]

William looked for help in managing his estate. He hired Mayer Amschel Rothschild as "Hoffaktor" in 1769,[1] to supervise the operation of his properties and tax-gathering. The wealth of William's estate provided a good living for Rothschild and the men had a strong relationship; he founded the Rothschild family dynasty, which became important in financing and banking in Europe. Although they had been acquainted since 1775, William IX did not formally designate Rothschild as his overseer until 1801.

The early fortunes of the Rothschild family were made through a conjunction of financial intelligence and the wealth of Prince William. During the Napoleonic Wars, William used the Frankfurt Rothschilds to hide his fortune from Napoleon. This money then saw its way through to Nathan Mayer, (N.M.) in London, where it helped fund the British movements through Portugal and Spain. The interest made from this venture was reaped by the budding banker barons, who used it to swiftly develop their fortune and prestige in Europe and Britain. It was not long before their riches outweighed those of their benefactor, William of Hesse-Kassel.

In 1803, Landgrave William was created His Royal and Serene Highness The Prince-Elector of Hesse.[2] In 1807 his electorate was annexed by the Kingdom of Westphalia, ruled by Jérôme Bonaparte, Napoleon's brother. William escaped to Denmark with his family and lived there in exile until the French were expelled from Germany. Following the defeat of the Napoleonic armies in the Battle of Leipzig, William was restored in 1813.

He was a member of the Tugendbund, a quasi-Masonic secret society founded after the Battle of Jena–Auerstedt in June 1808 at Koningsberg.

Several other prince-electors of the Holy Roman Empire had been recognized as kings at the Congress of Vienna (1815), and William attempted to join them by declaring himself King of the Chatti. However, the European powers refused to recognize this title at the Congress of Aix-la-Chapelle (1818) and instead granted him the grand ducal style of "Royal Highness."[3] Deeming the title of Prince-Elector to be superior in dignity to that of Grand Duke, William chose to remain an Elector, even though there was no longer a Holy Roman Emperor to elect. Hesse-Kassel would remain an Electorate until it was annexed by Prussia in 1866.

He ruled until his death in Kassel in 1821. He was succeeded by his son William.


Wilhelm I, his wife, Wilhelmine Caroline and their children, Wilhelm, Marie Friederike and Karoline Amalie.

With his wife Wilhelmina Caroline of Denmark and Norway he had four children:

He had several mistresses and fathered over twenty recognized illegitimate children and provided some financial means to each of them.

With his mistress Charlotte Christine Buissine:

  • Wilhelm of Heimrod (1775–1811)
  • Karl of Heimrod (1776–1827), married Charlotte von Stockhausen (1781–1855) in 1803 ; they had 7 children.
  • Friedrich of Heimrod (b. & d. 1777)
  • Friedrich of Heimrod (1778–1813) ; he had at least one son.

With his mistress Rosa Dorothea Ritter (1759–1833):

  • Wilhelm Karl of Haynau (1779–1856), married firstly Karoline von Schack (died 1807) in 1803, they had two children. Married secondly Luise Sophie Buderus von Carlshausen (1787–1813) in 1808, they had two children. Married thirdly Sophie Friederike von Lengerke (1798–1820) in 1818, no known issue survived to adulthood. Married fourthly Elisabeth Frn von Trott zu Solz (1793–1844) in 1822, they had three daughters.
  • Georg Wilhelm of Haynau (1781–1813), married Charlotte Sophie von Wildungen (1782–1858) in 1808 ; they had 3 children.
  • Philipp Ludwig of Haynau (1782–1843), married Wilhelmine von Zeppelin (1791–1872) in 1821 ; they had two children.
  • Wilhelmine of Haynau (1783–1866), married Karl Frhr von Hanstein (1771–1861) in 1801 ; they had 9 children.
  • Moritz of Haynau (1784–1812), married Anna Auguste von Wurmb (1789–1872) in 1809 ; they had 2 daughters.
  • Marie Sophie Agnes Philippine Auguste of Haynau (1785–1865), married Wilhelm Frhr von Wintzingerode (1782–1819) in 1805 ; they had one son.
  • Julius Heinrich Friedrich Ludwig of Haynau (1786–1853), married Theresia Weber von Treuenfels (1787–1851) in 1808 ; they had one daughter.
  • Otto of Hanau (1788–1791)

With his mistress Karoline von Schlotheim (1766–1847):

  • Wilhelm Friedrich of Hessenstein (1789–1790)
  • Wilhelm Karl of Hessenstein (1790–1867), married Angelika von Osten-Sacken (1802–1852) in 1820 ; they had one daughter.
  • Ferdinand of Hessenstein (1791–1794)
  • Karoline Frederike Auguste of Hessenstein (1792–1797)
  • Auguste Wilhelmine of Hessenstein (1793–1795)
  • Ludwig Karl of Hessenstein (1794–1857), married Auguste von Pückler (1794–1861).
  • Friederike of Hessenstein (1795–1855), married Wilhelm von Steuber (Kassel 29 Dec 1790-Kassel 6 Jun 1845) in 1824 ; they had 3 children.
  • Wilhelm Ludwig Georg of Hessenstein (1800–1836), married Luise von dem Bussche-Hünnefeld (1804–1829) in 1827 ; they had one son. Married secondly Karoline Wolff von Gudenburg (1812–1836) in 1831 ; they had 2 sons.
  • Friedrich Ludwig of Hessenstein (1803–1805)
  • Karoline of Hessenstein (1804–1891), married Karl von Stenglin (1791–1871) in 1822 ; they had 6 children.
  • stillborn child (1805)
  • stillborn child (1806)
  • stillborn child (1807)

See alsoEdit



  1. ^ Elon, Amos (1996). Founder: Meyer Amschel Rothschild and His Time. New York: HarperCollins. p. 65. ISBN 0-00-255706-1.
  2. ^ http://www.london-gazette.co.uk/issues/17365/pages/997
  3. ^ Satow, Ernest Mason (1932). A Guide to Diplomatic Practice. London: Longmans.
  4. ^ Genealogie ascendante jusqu'au quatrieme degre inclusivement de tous les Rois et Princes de maisons souveraines de l'Europe actuellement vivans [Genealogy up to the fourth degree inclusive of all the Kings and Princes of sovereign houses of Europe currently living] (in French). Bourdeaux: Frederic Guillaume Birnstiel. 1768. p. 58.

External linksEdit

William I, Elector of Hesse
Born: 3 June 1743 Died: 27 February 1821
Preceded by
William VIII
Count of Hanau-Münzenberg
1 February 1760 – 27 February 1821
Succeeded by
William II
Preceded by
Frederick II
Landgrave of Hesse-Kassel
31 October 1785 – 27 February 1821
New title Elector of Hesse
1803 – 27 February 1821