Royal intermarriage is the practice of members of ruling dynasties marrying into other reigning families. It was more commonly done in the past as part of strategic diplomacy for reasons of state. Although sometimes enforced by legal requirement on persons of royal birth, more often it has been a matter of political policy and/or tradition in monarchies.
From the medieval era until the fall of Napoleon I most European heads of state were hereditary monarchs in pursuit of national and international aggrandisement on behalf of themselves and their dynasties. Thus bonds of kinship tended to promote or restrain aggression. Marriage between dynasties could serve to initiate, re-enforce or guarantee peace between nations. Alternatively, kinship by marriage could secure an alliance between two dynasties which sought to reduce the sense of threat from or to initiate aggression against the realm of a third dynasty. It could also enhance the prospect of territorial acquisition for a dynasty by procuring legal claim to a foreign throne, or portions of its realm (e.g. colonies), through inheritance from an heiress whenever a monarch failed to leave an undisputed male heir.
Also following Europe's medieval era when tribal leaders evolved into feudal suzerains, suzerains into kings and kings into absolute monarchs, they rose from primus inter pares into God's anointed sovereigns. Marriages with subjects brought the king back down to the level of those he ruled, often stimulating the ambition of his consort's family and evoking jealousy—or disdain—from the nobility. The notion that monarchs should marry into the dynasties of other monarchs to end or prevent war was, at first, a policy driven by pragmatism. During the era of absolutism, it came to re-enforce the notion of Divine right—i.e., the premise that monarchs and dynasties were chosen to reign by God and, ipso facto, were different, as if by caste, rather than merely by fortune from their subjects. Kings continued to marry into the families of their greatest vassals down to the 16th century in most of Europe, by which time most of the great regional principalities and duchies were annexed to the Crown in Scandinavia, Latin Europe and the British Isles through royal subjugation or inheritance. Henceforth, kings tended to marry internationally and, increasingly, to have their sons and daughters do likewise.
- 1 Royal marriage as international policy
- 2 Inbreeding
- 3 Morganatic marriage
- 4 Modern examples in the post WWI era
- 5 Royal intermarriage outside of Europe
- 6 References
Royal marriage as international policy
Whereas the nobility in national monarchies often came to set great store by genealogical quarterings (a higher standard of noble ancestry, as measured by descent from four noble grandparents, eight noble great-grandparents, etc., rather than only in the male line), that standard proved less influential among reigning dynasties. Many European orders of chivalry (for men) and of canonesses (for women) imposed strict membership requirements for genealogical nobility extending back sometimes to all 64 of one's great-great-great grandparents or 300 years in a patriline. No such restrictions could apply to inter-marriage with reigning dynasties because the demand for political/military alliances and the prospect of inheritance of a foreign realm through marriage to its heiress forbade rigid adherence to standards of genealogical purity among Europe's ruling families: The Medici, Farnesi, Romanovs and Bonapartes were sought as marital partners by even Europe's oldest dynasties for these reasons.
Royal intermarriage was practised widely as a means of promoting mutually advantageous relations with neighboring or hostile nations by binding their reigning dynasties in blood kinship. As dynasties also approached absolutism and/or sought to preserve loyalty among competing members of the nobility, most eventually distanced themselves from kinship ties to local nobles by marrying abroad. In time, this practice contributed to the notion that it was socially as well as politically disadvantageous for members of ruling families to intermarry with their subjects. Queens consort selected from noble or common castes were sometimes subjected to scorn from their husbands' courtiers (e.g. Elizabeth Woodville, Karin Mansdotter and Anna Canalis di Cumiana).
Over time, due to the relatively limited number of potential consorts, the gene pool of many ruling families grew progressively smaller, until all European royalty were related. This also resulted in many being descended from a certain person through many lines of descent, such as the numerous European royalty and nobility descended from the British Queen Victoria or King Christian IX of Denmark. The House of Habsburg was infamous for its inbreeding, with the Habsburg lip cited as an ill-effect, although no genetic evidence has proved the allegation. The closely related houses of Habsburg, Bourbon, House of Braganza and Wittelsbach also engaged in first-cousin unions frequently and in double-cousin and uncle-niece marriages occasionally.
The entrenchment of the distinction between royalty and nobility gave rise to royal house laws among the sovereign houses of Europe and, particularly, among the semi-sovereign dynasties which reigned directly under the Holy Roman Emperor and held voting seats in his Imperial Diet. These laws either required the monarch's authorization for a dynastic marriage, or stipulated with whom a dynast must marry to comply with the principle of Ebenbürtigkeit, i.e., to contract an equal marriage, or both. Marriages which did not comply with this standard were considered non-dynastic, either being a mismarriage (inherently unequal, thus non-dynastic) or a morganatic marriage (unequal by mutual consent of the spouses or non-dynastic by monarchical decision).
If a member of a royal family marries someone of inappropriate status, that prince or princess often loses succession rights, titles, or various other royal privileges since nearly all monarchies impose legal restrictions on marriages of dynasts. A frequent occurrence in the past was for the spouse and any children to be denied any prospect of inheriting the dynasty's throne, and to be assigned lesser rank and titles than if the marriage had complied with the dynasty's norms: this was the morganatic marriage.
Sometimes these disinherited branches were deemed suitable for marriage into other families. This happened when Prince Alexander of Hesse and by Rhine married the lesser Countess Julia von Hauke. Julia and the morganatic children of this union were given the style of Serene Highness and title of Prince(ss) of Battenberg. The Battenberg family later married into the royal families of Sweden and Spain, and descendants into the royal families of Britain, Greece, Denmark, and other countries. Similarly, the Teck family, from which Queen Mary of the United Kingdom came, was a morganatic branch of the royal House of Württemberg.
Modern examples in the post WWI era
Members of two reigning houses
- Prince Nikolaus of Liechtenstein and Princess Margaretha of Luxembourg (1982, most recent example of intermarriage between two European dynasties reigning at the time of the wedding)
- Constantine II of Greece and Princess Anne Marie of Denmark (1964)
- Juan Carlos I of Spain and Princess Sophia of Greece (1962)
- Jean, Grand Duke of Luxembourg and Princess Joséphine Charlotte of Belgium (1953)
- Elizabeth II of the United Kingdom and Prince Philip of Greece and Denmark (1947)
- Peter II of Yugoslavia and Princess Alexandra of Greece and Denmark (1944)
- Prince Aimone, Duke of Aosta and Princess Irene of Greece (1939)
- Frederick IX of Denmark and Princess Ingrid of Sweden (1935)
- Prince George, Duke of Kent and Princess Marina of Greece and Denmark (1934)
- Knud, Hereditary Prince of Denmark and Princess Caroline-Mathilde of Denmark (1933)
- Umberto II of Italy and Princess Marie José of Belgium (1930)
- Boris III of Bulgaria and Princess Giovanna of Italy (1930)
- Olav V of Norway and Princess Märtha of Sweden (1929)
- Leopold III of Belgium and Princess Astrid of Sweden (1926)
- Alexander I of Yugoslavia and Princess Maria of Romania (1922)
- George II of Greece and Princess Elisabeth of Romania (1921)
- Carol II of Romania and Princess Helen of Greece (1921)
Members of one reigning house and one non-reigning house
- Princess Caroline of Monaco and Prince Ernst August of Hanover (1999)
- Alois, Hereditary Prince of Liechtenstein and Duchess Sophie in Bavaria (1993)
- Prince Gundakar of Liechtenstein and Princess Marie of France (1989)
- Princess Astrid of Belgium and Archduke Lorenz of Austria-Este (1984)
- Princess Marie Astrid of Luxembourg and Archduke Carl Christian of Austria (1982)
- Princess Barbara of Liechtenstein and Prince Alexander of Yugoslavia (1973)
- Princess Benedikte of Denmark and Richard, 6th Prince of Sayn-Wittgenstein-Berleburg (1968)
- Princess Irene of the Netherlands and Carlos Hugo, Duke of Parma (1964)
- Princess Birgitta of Sweden and Prince Johann Georg of Hohenzollern (1961)
- Princess Alix of Luxembourg and Antoine, 13th Prince of Ligne (1950)
- Princess Maria Francesca of Savoy and Prince Luigi of Bourbon-Parma (1939)
- Paul of Greece and Princess Frederica of Hanover (1938)
- Juliana of the Netherlands and Prince Bernhard of Lippe-Biesterfeld (1936)
- Prince Gustaf Adolf of Sweden, Duke of Västerbotten and Princess Sibylla of Saxe-Coburg and Gotha (1932)
- Princess Mafalda of Savoy and Philipp, Landgrave of Hesse (1925)
- Charlotte, Grand Duchess of Luxembourg and Prince Felix of Bourbon-Parma (1919)
Examples of multiple kinships
A well-known example of mid-20th century royal intermarriage was that of Elizabeth II of the United Kingdom and Prince Philip, Duke of Edinburgh (born a Prince of Greece and Denmark). Prince Philip is the son of Prince Andrew of Greece and Denmark and Princess Alice of Battenberg, whose mother Princess Victoria of Hesse and by Rhine and paternal grandfather, Prince Alexander of Hesse and by Rhine, were both members of the same paternal family.
Princess Alice's paternal uncle, Prince Henry of Battenberg married Princess Beatrice (a daughter of Elizabeth II's great-great-grandmother, Queen Victoria). Their daughter, Victoria Eugenie of Battenberg married King Alfonso XIII of Spain, and her grandson, the present king, Juan Carlos, married Princess Sophia of Greece & Denmark, whose father was a cousin of Prince Philip, Duke of Edinburgh.
Likewise, Queen Elizabeth's great-great-grandfather, King Christian IX of Denmark, was also Prince Philip's great-grandfather. They are also related several times through Princess Sophia, Electress of Hanover.
Although the royal house of Queen Elizabeth II is Windsor, it is agnatically the senior branch of the House of Saxe-Coburg and Gotha, to which King Albert II of Belgium also belongs. Their common male-line ancestor is Francis, Duke of Saxe-Coburg-Saalfeld (1750-1806). Elizabeth II's paternal great-great-great-grandfather was Ernest I, Duke of Saxe-Coburg and Gotha, whose youngest brother was Albert II's great-great-grandfather, Leopold I. Another paternal cousin of both Elizabeth II and Albert II of Belgium is ex-King Simeon II of Bulgaria, who is a male-line great-great-grandson of Prince Ferdinand of Saxe-Coburg and Gotha, himself the second son of Duke Francis and brother of both Ernest I and Leopold I.
Below is shown how each of Europe's ten currently reigning hereditary monarchs most closely relate to the current Queen of England. In addition to the relationships shown, there are many other common ancestors. The most recent common ancestor of all ten is John William Friso, Prince of Orange.
|Title||Monarch||Country||Cousin||Removed||Most recent common ancestors||Generations from John William Friso|
|Queen||Elizabeth II||United Kingdom||---||----||------||9|
|King||Harald V||Norway||2nd||none||Edward VII of the United Kingdom and Alexandra of Denmark||10|
|King||Carl XVI Gustaf||Sweden||3rd||none||Queen Victoria and Albert, Prince Consort||10|
|King||Juan Carlos I||Spain||3rd||none||Queen Victoria and Albert, Prince Consort||10|
|Queen||Margrethe II||Denmark||3rd||none||Christian IX of Denmark, Louise of Hesse-Kassel, Queen Victoria and Albert, Prince Consort||10|
|King||Philippe||Belgium||3rd||once||Christian IX of Denmark and Louise of Hesse-Kassel||10|
|Grand Duke||Henri||Luxembourg||3rd||once||Christian IX of Denmark and Louise of Hesse-Kassel||10|
|Frederick II Eugene, Duke of Württemberg and Friederike Dorothea of Brandenburg-Schwedt
Frederick Francis I, Grand Duke of Mecklenburg-Schwerin and Princess Louise of Saxe-Gotha-Altenburg
|Prince||Hans-Adam II||Liechtenstein||7th||once||John William Friso, Prince of Orange, and Marie Louise of Hesse-Kassel||10|
|Prince||Albert II||Monaco||7th||twice||John William Friso, Prince of Orange, and Marie Louise of Hesse-Kassel||11|
Grandchildren of Queen Victoria and King Christian IX
In early twentieth-century Europe, the grandchildren of Queen Victoria and King Christian IX were prevalent throughout most of Europe's royal courts. The British throne was occupied by King Edward VII, who was married to Princess Alexandra, the daughter of King Christian IX of Denmark. German Emperor William was the son of German Emperor Frederick III and Victoria, Princess Royal, the eldest daughter of Queen Victoria. Another of Victoria's daughters, Princess Alice, married Grand Duke Louis IV of Hesse and by Rhine, whose daughter Princess Alix became Empress of Russia as the consort of Tsar Nicholas II. Nicholas himself was the son of Tsar Alexander III and Princess Marie Sophie Frederikke Dagmar, another daughter of King Christian IX of Denmark.
Example of dynastic intra-marriage
Prince David Bagration of Mukhrani married Princess Anna Bagration-Gruzinsky on 8 February 2009 at the Tbilisi Sameba Cathedral. The marriage united the Bagration-Gruzinsky (Kakheti) and Bagration-Moukhransky (Mukhraneli) branches of the former royal family of Georgia, and drew a crowd of 3,000 spectators, officials, and foreign diplomats, as well as extensive coverage by the Georgian media.
The dynastic significance of the wedding lay in the fact that, amidst the turmoil in political partisanship that has roiled Georgia since its independence in 1991, Patriarch Ilia II of Georgia publicly called for restoration of the monarchy as a path toward national unity in October 2007.  Although this led some politicians and parties to entertain the notion of a Georgian constitutional monarchy, competition arose among the old Bagrationi dynasty's princes and supporters, as historians and jurists debated which Bagrationi has the strongest hereditary right to a throne that has been vacant for two centuries.
Aside from his unmarried elder brother, Prince David is the heir male of the Bagration family, while the bride's father, Prince Nugzar Bagration-Gruzinsky, is the most senior descendant of the last Bagrationi to reign over the united kingdom of Georgia. But the marriage between the Gruzinsky heiress and the Mukhrani heir resolves their rivalry for the claim to the throne, which has recently divided Georgian monarchists. The couple's first child, Prince Giorgi Bagration Bagrationi was born on September 27, 2011.
Royal intermarriage outside of Europe
Although the practice of royal intermarriage was most dominant in Europe, it was not unheard of nor frowned upon in other areas.
Ancient Roman client kingdoms
- Juba II&I, King of Numidia and Mauretania and Princess Glaphyra of Cappadocia
- Ptolemy, King of Mauretania and Julia Urania (possibly a minor Emesani princess)
- Sampsiceramus II, Priest-King of Emesa and Princess Iotapa of Commagene
- AD 56: Sohaemus, Priest-King of Emesa and Princess Drusilla of Mauretania
- Cotys III, King of Thrace and Princess Antonia Tryphaena of Pontus
- Tiberius Julius Aspurgus, King of the Bosporan Kingdom and Princess Gepaepyris of Thrace
- Rhoemetalces III, King of Thrace and Pythodoris II, Queen of Thrace
- Prince Alexander of Judea and Princess Glaphyra of Cappadocia
- Herod Archelaus, Ethnarch of Samaria and Princess Glaphyra of Cappadocia
- Polemon II, King of Pontus and Princess Berenice of Judea
- Gaius Julius Alexander, King of Cetis and Princess Julia Iotapa of Commagene
- Prince Aristobulus IV of Judea and Princess Berenice of Judea
- Prince Aristobulus Minor of Judea and Princess Iotapa of Emesa
- The reigning dynasties of Swaziland, KwaZulu-Natal and Transkei are related in the following fashion: Nelson Mandela belonged to a cadet branch of the Thembu dynasty, which reigns in the Transkeian Territories of South Africa's modern Eastern Cape province. His patrilineal great-grandfather Ngubengcuka, who died in 1832, ruled as the Inkosi Enkhulu, or king, of the Thembu people. One of the king's sons, named Mandela, became Nelson's grandfather and the source of his surname. However, because he was only the Inkosi's child by a wife of the Ixhiba clan, a so-called "Left-Hand House", the descendants of his branch of the royal family were morganatic, not eligible to succeed to the Thembu throne (cf. the so-called "left-hand marriage" of European history). Nonetheless, Nelson Mandela's father, Gadla Henry Mphakanyiswa, served as chief of Mvezo in the Transkei. The former South African president's daughter, Zeni Mandela, is married to Prince Thumbumuzi Dlamini, an elder brother of both Mswati III, reigning King of Swaziland, and of Queen Mantfombi Dlamini, the Great Wife of the reigning King of KwaZulu-Natal, Goodwill Zwelithini. Prince Thumbumuzi, King Mswati III and Queen Mantfombi are all children of the late King Sobhuza II of Swaziland. Queen Mantfombi's eldest son, Prince Misuzulu, is now a prime candidate to inherit his father's throne, becoming the next Zulu King. Meanwhile, the bond between the Xhosa dynasty to which Mandela belonged and the Zulu royal family, representing two of South Africa's largest ethnic groups, was renewed by another wedding, that in December 2002 of Mandela's great-nephew, Chief Nfundo Bovulengwe Mtirara of the Thembu, and King Goodwill Zwelithini's daughter, Princess Nandi Zulu.
In addition to the foregoing, a series of other royal unions have occurred throughout the continent of Africa's history. These other examples include the following:
- The marriage between King Solomon and the Queen of Sheba  that is described in the Kebra Negast of Ethiopia, a union that is said to be responsible for the birth of the Solomonic dynasty of that country.
- The Yoruba prince Omoba Oranyan of Ile-Ife married an Edo princess named Erinwinde just prior to his leaving Benin city, a union that led to the birth of the so-called Eweka dynasty of the Benin empire that has continued to rule the Edo people to this day.
- The Toucouleur emperor Umar Tall chose the daughter of the sultan Muhammed Bello of Sokoto as one of his wives, and the successors that inherited his spiritual authority in modern Senegal descend from the two of them.
- An unusual case is that of Nana Joe Appiah, an Ashanti royal of Ghana, who married the British socialite Peggy Cripps. She was a descendant of King William I of England through the line of the Cripps holders of the barony Parmoor.
Unlike in Europe, Chinese emperors were not quite as concerned about the dynastic status of their wives and concubines. Nevertheless, royal intermarriage was not uncommon in China. In times when there were several rival dynasties vying for control, Chinese rulers used royal intermarriage as a way to maintain a balance of power or to solidify alliances between states. In times when there was only one dynasty in China, emperors often married their daughters or other female members of their families to foreign leaders in order to maintain peace between their two nations. Most prominent were the marriages of countless Korean noblewomen to Chinese rulers. The tributary status of Korean kingdoms at times in history led to Korean noblewomen becoming secondary wives who rose to the status of empress. As a result of centuries of such practice, the Chinese imperial family came to be of majority Korean and eventually Manchurian blood, especially when the Manchu royal family ruled China in the period we know as the Qing Dynasty. This practice was also practiced in the reverse especially the Manchu rule of China which resulted in countless Manchurian princesses marrying into the Korean imperial family as a sign of mutual friendship. In turn, the high intermarriage rates of Korean nobles into the Japanese ruling class and Korean aristocrats being the progenitor of countless Japanese noble families and the Japanese royal family established a ruling class in Japan more closely related to Korea by blood then the native Japanese they ruled. This is acknowledged by Emperor Akihito of Japan mentioning this cultural link between Japan and Korea and the mainland in the hopes of ameliorating the tension between mainland East Asia and Japan.
The following Chinese royals married princes or princesses from other ruling families:
- In 582 A.D., Yang Guang, Prince of Jin (later Emperor Yang of Sui), the second son of Emperor Wen of Sui, married Princess Xiao of Western Liang, the daughter of Emperor Ming of Western Liang, a vassal of Emperor Wen, as his wife and consort. The marriage had been arranged by their fathers to seal an alliance between the their two states.
- In addition to Princess Xiao, Emperor Yang also took as a concubine Princess Chou, daughter of Chen Shubao, the last emperor of the Chen Dynasty.
- When Emperor Wen of Sui successfully conquered the Chen Dynasty, he took the defeated Chen emperor, Chen Shubao's, younger sister, Princess Ningyuan, as a concubine.
- Yang Yong, eldest son and initial crown prince of Emperor Wen of Sui, married Lady Yuan, daughter of official Yuan Xiaoju and a minor princess of the royal house of Northern Wei, as his crown princess.
- Yuwen Tai, paramount general (and later emperor) of Northern Zhou, married Princess Fengyi of Northern Wei as his second wife and consort.
- One of Yuwen Tai's daughters became the empress of Emperor Fei of Western Wei.
- Yuwen Jue, Duke of Lüeyang (later Emperor Xiaomin of Northern Zhou) married as his duchess Yuan Humo, the Princess Jin'an, fifth daughter of Emperor Wen of Western Wei.
- Emperor Xuan of Northern Zhou married as his empress Yang Lihua, eldest daughter of Emperor Wen of Sui.
- Emperor Taizong of Tang took a daughter of Emperor Yang of Sui as a concubine.
- Qing Dynasty emperor Huang Taiji married as his empress Princess Borjigit Jere, a member of the extended Mongolian imperial clan. He also took as concubines Jere's nieces Bumbutai and Harjol.
- Prince Pujie, second son of Zaifeng, Prince Chun and younger brother of Emperor Puyi, married as his first wife minor Manchurian princess Tung Tsih-shia in 1924. He divorced her two years later.
- Emperor Daowu of Northern Wei married the daughter of Murong Bao, the last emperor of Later Yan, as his wife and empress.
- In addition to Empress Murong, Emperor Daowu of Northern Wei also married the daughter of Xiongnu chief Liu Toujuan as his concubine
- Emperor Taiwu of Northern Wei married as his empress a daughter of Helian Bobo, founding emperor of Xia. He also took Empress Helian's two younger sisters as concubines.
- Helian Bobo married Lady Mo, a daughter of Xianbei chief Mo Yigan, as his first wife and consort.
- Emperor Wen of Western Wei married as his second empress Lady Yujiulü, the daughter of Yujiulü Anagui, Chiliantoubingdoufa Khan of Rouran.
- Princess Taihe of Tang, tenth daughter of Emperor Xianzong of Tang, married Chongde Khan, ruler of Huigu, as his Kedun (equivalent to the Chinese empress.
- Princess Wencheng, a relation to the Tang Dynasty imperial clan, married Songtsän Gampo, thirty-third king of the Yarlung Dynasty in Tibet.
- Princess Anhua of Tang, second daughter of Emperor Xianzong of Tang, married Longshun, ruler of Nanzhao.
- Helian Chang married Princess Shiping of Northern Wei, sister of Emperor Taiwu of Northern Wei and daughter of Emperor Mingyuan of Northern Wei, as his second wife and empress.
- Emperor Wencheng of Northern Wei married as his empress Lady Feng, granddaughter of last emperor of Northern Yan Feng Hong.
Royal intermarriage existed in Korea, but was not widespread except during the Three Kingdoms of Korea period.
The following are several examples of Korean royal intermarriage:
- The Silla Kingdom had a practice that limited the succession to the throne to members of the seonggol, or "sacred bone", rank. To maintain their "sacred bone" rank, members of this caste often intermarried with one another in the same fashion that European royals intermarried to maintain a "pure" royal pedigree.
- Princess Seonhwa of Silla, daughter of King Jinpyeong of Silla and sister of Queen Seondeok, is thought to have married King Mu of Baekje in a rare incident of royal intermarriage between a seonggol Silla princess and a royal from another Korean kingdom.
- Members of the Silla royal family who were not seonggol were considered jingol, or "true bone". Although not dynasts (in essence they were morganatic members of the royal clan), they were often still of pure royal or aristocratic blood, as jingol often married members of the noble Bak and Seok clans of Gyeongju, Nagan or the Kimhae Kim clan, a branch of the royal house of Geumgwan Gaya.
- In 1920, Crown Prince Euimin of Korea was married to Princess Masako of Nashimoto. The marriage was arranged by the Japanese in an attempt to introduce Japanese blood into the Korean royal line.
- Mohammed Reza Pahlavi of Iran and Princess Fawzia Fuad of Egypt (1939–1948)
- HH Sheikh Mohammed bin Rashid Al Maktoum of Dubai to Her Royal Highness Princess Haya bint Hussein of Jordan
- HH Sheikh Mohammed bin Hamad bin Mohammed Al Sharqi crown prince of Fujairah to HH Sheikha Latifa bint Mohammed bin Rashid Al Maktoum
- HH Sheikh Nasser bin Hamad Al Khalifa of Bahrain to HH Sheikha Shaikha bint Mohammed bin Rashid Al Maktoum
- HH Sheikh Mansour bin Zayed Al Nahyan of Abu Dhabi to HH Sheikha Manal bint Mohammed bin Rashid Al Maktoum
- HRH Muhammad Ali, Prince of the Sa'id, elder son of ex-King Fuad II of Egypt, to Princess Noal Zaher Shah granddaughter of deposed King Zahir Shah of Afghanistan, on 30 August 2013 at Istanbul.
- Thomson, David (1961). "The Institutions of Monarchy". Europe Since Napoleon. New York: Knopf. pp. 79–80. "The basic idea of monarchy was the idea that hereditary right gave the best title to political power...The dangers of disputed succession were not avoided by hereditary succession: ruling families had a natural interest in passing on to their descendants enhanced power and prestige...Frederick the Great of Prussia, Catherine the Great of Russia, Maria Theresa of Austria, were alike infatuated with the idea of strengthening their power, centralizing government in their own hands as against local and feudal privileges, and so acquiring more absolute authority in the state. Moreover, the very dynastic rivalries and conflicts between these eighteenth-century monarchs drove them to look for ever more efficient methods of government"
- Durant, Will. The Story of Civilzation: The Age of Faith, volume IV. Feudalism and Chivalry. Simon and Schuster, New York, 1950, pp.552-553, 564-566, 569, 571, 573, 576.
- Beeche, Arturo (2009). The Gotha: Still a Continental Royal Family, Vol. 1. Richmond, US: Kensington House Books. pp. 1–13. ISBN 9-7809-7719-6173.
- Zoepfl, Heinrich. Grundsätze des gemeinen deutschen Staatsrechts, 5th edition. Der Fürst und sein Haus oder das Familien- und Thronerbrecht der souverainen deutschen Familien. C. F. Winter'sche Verlagshandlung, 1863, Leipzig, pp. 583-759. In German.
- Rehm, Hermann. Modernes Fürstenrecht. Ebenbürtigkeit. J. Schweitzer Verlag, 1904, Munich, pp. 151-179. In German.
- sometimes considered a marriage between two reigning dynasties because Ernst August is a direct descendant in the legitimate male line of George III of Great Britain, eligible to transmit British succession rights to his descendants, subject to the Royal Marriages Act 1772 and the couple's marriage required the official consent of the governments of Monaco, France and the United Kingdom
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- Guiloineau, Jean; Rowe, Joseph (2002). Nelson Mandela: the early life of Rolihlahla Mandiba. North Atlantic Books. p. 13. ISBN 1-55643-417-0.
- Keller, Bill (1994-09-21). "Zulu King Breaks Ties To Buthelezi". The New York Times. Retrieved 2008-04-29.
- Hlongwane, Wonder (2 September 2000). "Right Royal Row Divides Zwelithini's Court". News24 (Cape Town). Retrieved 2013-04-07.
- "Wedding Brings Xhosa, Zulu Tribes Together". Los Angeles Times (California). 9 December 2002. Retrieved 2013-04-07.
- Thusi, Mbali (7 December 2002). "Xhosa, Zulu Royal Houses Unite in Marriage". IOL News. South Africa: Independent Newspapers. Retrieved 2013-04-07.
- The Kebra Nagast as translated by E.A.W. Budge, Internet Sacred Text Archive
- Daughter of Yuan Huai, Prince Wumu of Guangping, granddaughter of Emperor Xiaowen of Northern Wei, and sister of Emperor Xiaowu of Northern Wei
- Members of the "sacred bone rank" were often members of the Silla royal house by both birth and marriage. It was not abnormal to find a Silla king or prince with a wife (and even concubines) who were princesses of Silla in their own right (that is, by birth).
- Hello Magazine Prince Muhammed Ali of Egypt and Princess Noal Zaher of Afghanistan Prepare for their Royal Wedding. 2 August 2013 (retrieved 26 November 2013).
- Arabia weddings. Royal Wedding of Prince Muhammad Ali of Egypt and Princess Noal Zaher. 16 September 2013 (retrieved 26 November 2013).