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 national interest. Although sometimes enforced by legal requirement on persons of royal birth, more often it has been a matter of political policy or tradition in monarchies.
In Europe, the practice was most prevalent from the medieval era until the outbreak of World War I, but evidence of intermarriage between royal dynasties in other parts of the world can be found as far back as the Late Bronze Age. Monarchs were often 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, reinforce 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.
In parts of Europe, royalty continued to regularly marry into the families of their greatest vassals as late as the 16th century. More recently, they have tended to marry internationally. In other parts of the world royal intermarriage was less prevalent and the number of instances varied over time, depending on the culture and foreign policy of the era.
It was not until the study of genetics began in the early twentieth century that the harm caused by inbreeding was recognized. For modern observers, it is easy to see its relation to royal biological problems, most noticeably in the case of the last Spanish Habsburg monarch, Charles II of Spain, incapable of procreation and suffering from a pronounced underbite - the Habsburg jaw.
While the contemporary Western ideal sees marriage as a unique bond between two people who are in love, families in which heredity is central to power or inheritance (such as royal families) have often seen marriage in a different light. There are often political or other non-romantic functions that must be served and the relative wealth and power of the potential spouses may be considered. Marriage for political, economic, or diplomatic reasons, the marriage of state, was a pattern seen for centuries among European rulers.
At times, marriage between members of the same dynasty has been common in Central Africa.
In West Africa, the sons and daughters of Yoruba kings were traditionally given in marriage to their fellow royals as a matter of dynastic policy. Sometimes these marriages would involve members of other tribes. Erinwinde of Benin, for example, was taken as a wife by the ObaOranyan of Oyo during his time as governor of Benin. Their son Eweka went on to found the dynasty that ruled the Kingdom of Benin.
The Chakri Dynasty of Thailand has included marriages between royal relatives, but marriages between dynasts and foreigners, including foreign royals, are rare. This is in part due to Section 11 of 1924 Palace Law of Succession which excludes members of the royal family from the line of succession if they marry a non-Thai national.
The Lý dynasty which ruled Dai Viet (Vietnam) married its princesses off to regional rivals to establish alliances with them. One of these marriages was between a Lý empress regnant (Lý Chiêu Hoàng) and a member of the Chinese Trần (Chen) clan (Trần Thái Tông), which enabled the Trần to then topple the Lý and established their own Trần dynasty.
A Lý princess also married into the Hồ family, which was also of Chinese origin and later established the Hồ dynasty which also took power after having a Tran princess marry one of their members, Hồ Quý Ly.
Marriage policy in imperial China differed from dynasty to dynasty. Several dynasties practiced Heqin, which involved marrying off princesses to other royal families.
The Xiongnu practiced marriage alliances with Han dynasty officers and officials who defected to their side. The older sister of the Chanyu (the Xiongnu ruler) was married to the Xiongnu General Zhao Xin, the Marquis of Xi who was serving the Han dynasty. The daughter of the Chanyu was married to the Han Chinese General Li Ling after he surrendered and defected. The Yenisei Kirghiz Khagans claimed descent from Li Ling. Another Han Chinese General who defected to the Xiongnu was Li Guangli who also married a daughter of the Chanyu.
When the Eastern Jin dynasty ended Northern Wei received the Jin prince Sima Chuzhi 司馬楚之 as a refugee. A Northern Wei Princess married Sima Chuzhi, giving birth to Sima Jinlong 司馬金龍. Northern Liang King Juqu Mujian's daughter married Sima Jinlong.
The Kingdom of Gaochang was made out of Han Chinese colonists and ruled by the Han Chinese Qu family which originated from Gansu. Jincheng commandery 金城 (Lanzhou), district of Yuzhong 榆中 was the home of the Qu Jia. The Qu family was linked by marriage alliances to the Turks, with a Turk being the grandmother of King Qu Boya.
Tang dynasty (618–907) emperors gave princesses in marriage to rulers of the Uyghur Khaganate to consolidate the special trade and military relationship that developed after the Khaganate supported the Chinese during the An Lushan Rebellion. At least three Tang imperial princesses are known to have married khagans between 758 and 821. These unions temporarily stopped in 788, which is believed in part to be because stability within the Chinese empire meant that they were politically unnecessary; however, threats from Tibet in the west, and a renewed need for Uyghur support, precipitated the marriage of Princess Taihe to Bilge Khagan.
The ethnically Chinese Cao family ruling Guiyi Circuit established marriage alliances with the Uighurs of the Ganzhou Kingdom, with both the Cao rulers marrying Uighur princesses and with Cao princesses marrying Uighur rulers. The Ganzhou Uighur Khagan's daughter was married to Cao Yijin in 916.
The Chinese Cao family ruling Guiyi Circuit established marriage alliances with the Saka Kingdom of Khotan, with both the Cao rulers marrying Khotanese princesses and with Cao princesses marrying Khotanese rulers. A Khotanese princess who was the daughter of the King of Khotan married Cao Yanlu.
The KhitanLiao dynasty arranged for women from the Khitan royal consort Xiao clan to marry members of the Han Chinese Han 韓 clan, which originated in Jizhou 冀州 before being abducted by the Khitan and becoming part of the Han Chinese elite of the Liao.
Han Chinese Geng family intermarried with the Khitan and the Han 韓 clan provided two of their women as wives to Geng Yanyi and the second one was the mother of Geng Zhixin. Empress Rende's sister, a member of the Xiao clan, was the mother of Han Chinese General Geng Yanyi.
Han Durang (Yelu Longyun) was the father of Queen dowager of State Chen, who was the wife of General Geng Yanyi and buried with him in his tomb in Zhaoyang in Liaoning. His wife was also known as "Madame Han". The Geng's tomb is located in Liaoning at Guyingzi in Chaoying.
Emperors of the proceeding Song dynasty (960–1279) tended to marry from within their own borders. Tang emperors, mainly took their wives from high-ranking bureaucratic families, but the Song dynasty did not consider rank important when it came to selecting their consorts. It has been estimated that only a quarter of Song consorts were from such families, with the rest being from lower status backgrounds. For example, Liu, consort of Emperor Zhenzong, had been a street performer and consort Miao, wife of Emperor Renzong was the daughter of his own wet nurse.
During the Qing dynasty (1644–1912), emperors chose their consorts primarily from one of the eight Banner families, administrative divisions that divide all native Manchu families. To maintain the ethnic purity of the ruling dynasty, after the Kangxi Period (1662–1722), emperors and princes were forbidden to marry non-Manchu wives. Imperial daughters however were not covered by this ban, and as with their preceding dynasties, were often married to Mongol princes to gain political or military support, especially in the early years of the Qing dynasty; three of the nine daughters of Emperor Nurhaci and twelve of Emperor Hongtaiji's daughters were married to Mongol Princes.
The Manchu Imperial Aisin Gioro clan practiced marriage alliances with Han Chinese Ming Generals and Mongol princes. Aisin Gioro women were married to Han Chinese Generals who defected to the Manchu side during the Manchu conquest of China. The Manchu leader Nurhaci married one of his granddaughters to the Ming General Li Yongfang李永芳 after he surrendered Fushun in Liaoning to the Manchu in 1618 and a mass marriage of Han Chinese officers and officials to Manchu women numbering 1,000 couples was arranged by Prince Yoto 岳托 (Prince Keqin) and Hongtaiji in 1632 to promote harmony between the two ethnic groups. Aisin Gioro women were married to the sons of the Han Chinese Generals Sun Sike (Sun Ssu-k'o) 孫思克, Geng Jimao (Keng Chi-mao), Shang Kexi (Shang K'o-hsi), and Wu Sangui (Wu San-kuei).
Nurhaci's son Abatai's daughter was married to Li Yongfang. The offspring of Li received the "Third Class Viscount" (三等子爵; sān děng zǐjué) title. Li Yongfang was the great great great grandfather of Li Shiyao 李侍堯.
The "Dolo efu" 和碩額駙 rank was given to husbands of Qing princesses. Geng Zhongming, a Han bannerman, was awarded the title of Prince Jingnan, and his son Geng Jingmao managed to have both his sons Geng Jingzhong and Geng Zhaozhong 耿昭忠 become court attendants under the Shunzhi Emperor and get married to Aisin Gioro women, with Prince Abatai's granddaughter marrying Geng Zhaozhong 耿昭忠 and Haoge's (a son of Hong Taiji) daughter marrying Geng Jingzhong. A daughter 和硕柔嘉公主 of the Manchu Aisin Gioro Prince Yolo 岳樂 (Prince An) was wedded to Geng Juzhong 耿聚忠 who was another son of Geng Jingmao.
The 4th daughter of Kangxi (和硕悫靖公主) was wedded to the son (孫承恩) of the Han Chinese Sun Sike (Sun Ssu-k'o) 孫思克.
The wedding photo of Crown Prince Yi Un of Korea and Japanese Princess Masako of Nashimoto
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.
The Goryeo Dynasty had a history of incestuous marriage within the royal family in its early years, starting from Gwangjong, the fourth king, who married his half-sister Queen Daemok. To avoid scandals, the female members of the dynasty would be ceremonially adopted by their maternal families after birth. This practice of dynastic incest ended with the overthrow of Queen Heonae, the mother of Mokjong, the seventh king, after she attempted to seize the throne for herself and her illegitimate sons by placing these sons as Mokjong's heir, only to be foiled by a coup masterminded by the Goryeo general Gang Jo.
Careful selection of a spouse was important to maintain the royal status of a family: depending on the law of the land in question, if a prince or king was to marry a commoner who had no royal blood, even if the first-born was acknowledged as a son of a sovereign, he might not be able to claim any of the royal status of his father.
Traditionally, many factors were important in arranging royal marriages. One such factor was the amount of territory that the other royal family governed or controlled. Another, related factor was the stability of the control exerted over that territory: when there was territorial instability in a royal family, other royalty would be less inclined to marry into that family. Another factor was political alliance: marriage was an important way to bind together royal families and their countries during peace and war and could justify many important political decisions.
The increase in royal intermarriage often meant that lands passed into the hands of foreign houses, when the nearest heir was the son of a native dynasty and a foreign royal.[n 1][n 2] The Habsburgs, for example, expanded their influence through arranged marriages and by gaining political privileges in what would become Switzerland, and in the 13th century the house aimed its marriage policy at families in Upper Alsace and Swabia. Given the success of the Habsburgs' territorial acquisition-via-inheritance policy, a motto came to be associated with their dynasty: Bella gerant alii, tu, felix Austria, nube! ("Let others wage war. You, happy Austria, marry!")
Monarchs sometimes went to great lengths to prevent this. On her marriage to Louis XIV of France, Maria Theresa, daughter of Philip IV of Spain, was forced to renounce her claim to the Spanish throne. When monarchs or heirs apparent wed other monarchs or heirs, special agreements, sometimes in the form of treaties, were negotiated to determine inheritance rights. The marriage contract of Philip II of Spain and Mary I of England, for example, stipulated that the maternal possessions, as well as Burgundy and the Low Countries, were to pass to any future children of the couple, whereas the remaining paternal possessions (including Spain, Naples, Sicily, Milan) would first of all go to Philip's son Don Carlos, from his previous marriage to Maria Manuela of Portugal. If Carlos were to die without any descendants, only then would they pass to the children of his second marriage. On the other hand, the Franco-Scottish treaty that arranged the 1558 marriage of Mary, Queen of Scots and Francis, the son and heir of Henry II of France, had it that if the queen died without descendants, Scotland would fall to the throne of France.
Religion has always been closely tied to European political affairs, and as such it played an important role during marriage negotiations. The 1572 wedding in Paris of the French princess Margaret of Valois to the leader of France's Huguenots, Henry III of Navarre, was ostensibly arranged to effect a rapprochement between the nation's Catholics and Protestants, but proved a ruse for the St. Bartholomew's Day massacre. After the English Reformation, matches between English monarchs and Roman Catholic princesses were often unpopular, especially so when the prospective queen consort was unwilling to convert, or at least practice her faith discreetly.[n 3] Passage of the Act of Settlement 1701 disinherited any heir to the throne who married a Catholic. Other ruling houses, such as the Romanovs[n 4] and Habsburgs, have at times also insisted on dynastic marriages only being contracted with people of a certain faith or those willing to convert. When in 1926 Astrid of Sweden married Leopold III of Belgium, it was agreed that her children would be raised as Catholics but she was not required to give up Lutheranism, although she chose to convert in 1930. Some potential matches were abandoned due to irreconcilable religious differences. For example, plans for the marriage of the Catholic Władysław IV Vasa and the Lutheran Elisabeth of Bohemia, Princess Palatine proved unpopular with Poland's largely Catholic nobility and were quietly dropped.
Marriages among ruling dynasties and their subjects have at times been common, with such alliances as that of Edward the Confessor, King of England with Edith of Wessex and Władysław II Jagiełło, King of Poland with Elizabeth Granowska being far from unheard of in medieval Europe. However, as dynasties approached absolutism and sought to preserve loyalty among competing members of the nobility, most eventually distanced themselves from kinship ties to local nobles by marrying abroad. 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, 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 and pass over the opportunity for marriage into a foreign dynasty.
The Grand Komnenoi of the Empire of Trebizond were famed for marrying their daughters to their neighbours as acts of diplomacy.[n 6]Theodora Megale Komnene, daughter of John IV, was married to Uzun Hassan, lord of the Aq Qoyunlu, to seal an alliance between the Empire and the so-called White Sheep. Although the alliance failed to save Trebizond from its eventual defeat, and despite being a devout Christian in a Muslim state, Theodora did manage to exercise a pervasive influence both in the domestic and foreign actions of her husband.
Though usually made to strengthen the position of the empire, there are examples of interdynastic marriages destabilising the emperor's authority. When Emperor Andronikos II Palaiologos married his second wife, Eirene of Montferrat, in 1284 she caused a division in the Empire over her demand that her own sons share in imperial territory with, Michael, his son from his first marriage. She resorted to leaving Constantinople, the capital of the Byzantine Empire, and setting up her own court in the second city of the Empire, Thessalonica.
The marriages of Ottoman sultans and their sons in the fourteenth and fifteenth centuries tended to be with members of the ruling dynasties of neighbouring powers. With little regard for religion, the sultans contracted marriages with both Christians and Muslims; the purpose of these royal intermarriages were purely tactical. The Christian Byzantines and Serbians, as well as the Muslim beyliks of Germiyan, Saruhan, Karaman and Dulkadir were all potential enemies and marriage was seen as a way of securing alliances with them. Marriage with foreign dynasties seems to have ceased in 1504, with the last marriage of a sultan to a foreign princess being that of Murad II and Mara Branković, daughter of the Serbian ruler Đurađ Branković, in 1435. By this time, the Ottomans had consolidated their power in the area and absorbed or subjugated many of their former rivals, and so marriage alliances were no longer seen as important to their foreign policy.
The Islamic principle of kafa'a discourages the marriages of women to men of differing religion or of inferior status.[n 9] Neighbouring Muslim powers did not start to give their daughters in marriage to Ottoman princes until the fifteenth century, when they were seen to have grown in importance. This same principle meant that, while Ottoman men were free to marry Christian women, Muslim princesses were prevented from marrying Christian princes.
Royal incest was extremely common in the Kingdom of Hawaii and its predecessors, despite being rare in other Polynesian societies. Among the aliʻi, the ruling class, marriage between blood relatives of the first degree was believed to produce children with the highest rank under the kapu system, equal to that of the gods. A marriage between brother and sister was considered "the most perfect and revered union". It was believed that the mana of a particular aliʻi could be increased by incestuous unions. According to O. A. Bushnell, "in several accounts about Hawaiians, an ali’i who was the issue of an incestuous marriage [...] was noted for a splendid body and a superior intelligence". Writers have suggested that this preference for brother–sister incest came about as a way to protect the royal bloodline. Notable instances of incestuous relationships among Hawaiian royalty were those between King Kamehameha II and his half-sister Kamāmalu, which was a fully fledged marriage, and between Kamehameha III and his full sister Nahienaena. In the latter case, the siblings had hoped to marry but their union was opposed by Christian missionaries.
At one time, some dynasties adhered strictly to the concept of royal intermarriage. The Habsburgs, Sicilian and Spanish Bourbons and Romanovs, among others, introduced house laws which governed dynastic marriages; it was considered important that dynasts marry social equals (i.e., other royalty), thereby ruling out even the highest-born non-royal nobles. Those dynasts who contracted undesirable marriages often did so morganatically. Generally, this is a marriage between a man of high birth and a woman of lesser status (such as a daughter of a low-ranked noble family or a commoner). Usually, neither the bride nor any children of the marriage has a claim on the bridegroom's succession rights, titles, precedence, or entailed property. The children are considered legitimate for all other purposes and the prohibition against bigamy applies.
Over time, because of the relatively limited number of potential consorts, the gene pool of many ruling families grew progressively smaller, until all European royalty was related. This also resulted in many being descended from a certain person through many lines of descent, such as the numerous European royalty descended from Queen Victoria of the United Kingdom or King Christian IX of Denmark. The House of Habsburg was infamous for 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, Braganza and Wittelsbach[n 10] also engaged in first-cousin unions frequently and in double-cousin and uncle-niece marriages occasionally.
Examples of incestuous marriages and the impact of inbreeding on royal families include:
All rulers of the Ptolemaic dynasty from Ptolemy II were married to their brothers and sisters, in order to keep the Ptolemaic blood "pure" and to strengthen the line of succession. King Tutankhamun's father and mother were related. Cleopatra VII (also called Cleopatra VI) and Ptolemy XIII, who married and became co-rulers of ancient Egypt following their father's death, are the most widely known example.
Jean V of Armagnac was said to have formed a rare brother-sister liaison, left descendants and claimed to be married. There is no evidence that this "marriage" was contracted for dynastic rather than personal reasons.
One of the most famous examples of a genetic trait aggravated by royal family intermarriage was the House of Habsburg, which inmarried particularly often and is known for the mandibular prognathism of the Habsburger (Unter) Lippe (otherwise known as the 'Habsburg jaw', 'Habsburg lip' or 'Austrian lip'"). This was typical for many Habsburg relatives over a period of six centuries.
^Donald MacGillivray Nicol says in The Last Centuries of Byzantium 1261–1453: "The daughters of Alexios II Grand Komnenos married the emirs of Sinope and of Erzindjan, his granddaughters married the emir of Chalybia and the Turkoman chieftain of the so-called Ak-Koyunlu, or horde of the White Sheep; his great-granddaughters, the children of Alexios III, who died in 1390, performed even greater service to the Empire."
^Carolyn Fluehr-Lobban explains in her article Islamic Law and Society in the Sudan that "It is preferable that a non-Muslim convert to Islam before marriage to a Muslim man, however, it is not essential - it is essential that a non-Muslim man convert to Islam before contemplating marriage with a Muslim woman"
^The Wittlesbach line suffered from several cases of mental illness, often attributed to their frequent intermarriages. Several family members suffered from mental and physical illnesses, as well as epilepsy
^Mai Thục, Vương miện lưu đày: truyện lịch sử, Nhà xuất bản Văn hóa - thông tin, 2004, p.580; Giáo sư Hoàng Xuân Việt, Nguyễn Minh Tiến hiệu đính, Tìm hiểu lịch sử chữ quốc ngữ, Ho Chi Minh City, Công ty Văn hóa Hương Trang, pp.31-33; Helen Jarvis, Cambodia, Clio Press, 1997, p.xxiii.
^Gao Huan, as demanded by Yujiulü Anagui as one of the peace terms between Eastern Wei and Rouran, married the Princess Ruru in 545, and had her take the place of Princess Lou as his wife, but never formally divorced Princess Lou. After Gao Huan's death, pursuant to Rouran customs, the Princess Ruru became married to Gao Huan's son Gao Cheng, who also, however, did not formally divorce his wife.
Fluehr-Lobban, Carolyn (1987). "Islamic Law and Society in the Sudan". Islamic Studies (3 ed.). Islamabad, Pakistan: Islamic Research Institute, International Islamic University. 26 (3): 280–282. JSTOR20839848.
Frassetto, Michael (2003). Encyclopedia of Barbarian Europe: Society in Transformation. California, US: ABC-CLIO Ltd. ISBN9781576072639.
Garland, Lynda (2002). Byzantine Empresses: Women and Power in Byzantium AD 527–1204. Oxford, UK: Routledge. ISBN9781134756391.
Guyenne, Valois (2001). Incest and the Medieval Imagination. Oxford: Oxford University Press. ISBN9780861932269.