Primogeniture (English: /praɪməˈdʒɛnɪtʃər/) is the right, by law or custom, of the firstborn legitimate son to inherit his parent's entire or main estate, in preference to shared inheritance among all or some children, a child other than the eldest male, a daughter, illegitimate child or a collateral relative. In some cases the estate may instead be the inheritance of the firstborn child or occasionally the firstborn daughter. The descendant (often the son) of a deceased elder sibling (typically elder brother) inherits before a living younger sibling by right of substitution for the deceased heir. In the absence of any children, brothers succeed, individually, to the inheritance by seniority of age (subject to substitution). Among siblings, sons usually inherit before daughters. In the absence of male descendants in the male-line, there are variations of primogeniture which allocate the inheritance to a daughter or a brother or, in the absence of either, to another collateral relative, in a specified order (e.g. male-preference primogeniture, Salic primogeniture, semi-Salic primogeniture).

The principle has applied in history to inheritance of real property (land) as well as inherited titles and offices, most notably monarchies, continuing until modified or abolished.

Variations on primogeniture modify the right of the first-born son to the entirety of a family's inheritance (see appanage) or, in the West since World War II, eliminate the preference for males over females (absolute primogeniture). Most monarchies in Western Europe have eliminated male preference in succession: Belgium, Denmark, Luxembourg, Netherlands, Norway, Sweden and the United Kingdom.

Primogeniture has not been the only form of inheritance in monarchies.

The Holy Roman Emperor was selected for enthronement by a small number of powerful prince electors from among Europe's Christian males of inherited nobility. Currently, succession to the Saudi Arabian throne uses a form of lateral agnatic seniority, as did the Kievan Rus' (see Rota system), the early Kingdom of Scotland (see Tanistry), the Mongol Empire (see lateral succession) or the later Ottoman Empire (see succession practices).

Absolute, equal, or lineal primogeniture is a form of primogeniture in which gender is irrelevant for inheritance. No modern monarchy before 1980 practiced this form of primogeniture.^[1]

However, according to Poumarede (1972), the Basques of the Kingdom of Navarre transmitted title and property to the firstborn regardless of sex.^[2] The higher nobility and free families of the early and high middle ages followed this custom.^[2] The Navarrese monarchy, however, was inherited by dynasties from outside of Navarre, which followed different successional laws, usually male preference primogeniture. Eventually only the Basque lower nobility and free families of the Basque country and other regions continued to follow this custom, which persisted as late as the 19th century.^[2]

An ancient and alternative way in which women succeeded to power, especially without displacing the direct male line descendants of the first monarchs, is the historical consortium or coregency between husband, and wife or other relatives. The most notable of these are the Egyptian cases of Hatshepsut and Thutmose III, and the monarchs of the Ptolemaic Dynasty.

In 1980, Sweden amended its constitution to adopt royal succession by absolute primogeniture, displacing King Carl XVI Gustaf's infant son, Prince Carl Philip, in favor of his elder daughter, Princess Victoria, in the process. Several monarchies have since followed suit: the Netherlands in 1983, Norway in 1990, Belgium in 1991, Denmark in 2009, Luxembourg in 2011, and the United Kingdom and the other Commonwealth realms (for people born after October 2011) in 2015.

Monaco, the Netherlands, and Norway also deviated from traditional primogeniture in the late 20th or early 21st century by restricting succession to the crown to relatives within a specified degree of kinship to the most recent monarch.

Recently, other monarchies have changed or considered changing to absolute primogeniture:

Under agnatic primogeniture, or patrilineal primogeniture, the degree of kinship (of males and females) is determined by tracing shared descent from the nearest common ancestor through male ancestors.^[5] Those who share agnatic kinship (through solely male ancestors) are termed "agnates"; those whose shared lineage includes a female ancestor are "cognates".

There were different types of succession based on agnatic primogeniture, all sharing the principle that inheritance is according to seniority of birth among siblings (compare to ultimogeniture) and seniority of lineage among the agnatic kin, firstly, among the sons of a monarch or head of family, with sons and their male-line issue inheriting before brothers and their issue. Females and female-line descendants are excluded from succession.

Male-preference primogeniture accords succession to the throne to a female member of a dynasty if and only if she has no living brothers and no deceased brothers who left surviving legitimate descendants. A dynast's sons and their lines of descent all come before that dynast's daughters and their lines. Older sons and their lines come before younger sons and their lines. Older daughters and their lines come before younger daughters and their lines.

It was practiced in the succession to the once-separate thrones of England and Scotland (until their union under James VI and I) and then the United Kingdom until 2015, when the Succession to the Crown Act 2013 changed it to absolute primogeniture. The rule change also applies to all Commonwealth realms that have the British monarch as their head of state.

Male-preference primogeniture is currently practiced in succession to the thrones of Monaco and Spain (before 1700 and since 1830).

With respect to hereditary titles, it is usually the rule for Scotland and baronies by writ in the United Kingdom, but baronies by writ go into abeyance when the last male titleholder dies leaving more than one surviving sister or more than one descendant in the legitimate female line of the original titleholder.

An agnatic seniority primogeniture system that excludes any female from inheritance of a monarch's principal possessions is generally known in western Europe as an application of the "Salic law" (see Terra salica). This rule of succession developed in the course of a series of successions in France in the later Middle Ages. In 1316, Joan, the only surviving child of Louis X of France was debarred from the throne in favor of her uncle, Philip, Count of Poitiers. After this it was declared that women could not inherit the French throne. Then in 1328, after the death of Charles IV, Philip, Count of Valois (Charles IV's paternal cousin) became king, notwithstanding the claims of Edward III of England. By proximity of blood, Edward was the closest relative to the dead king, as he was the son of the king's sister Isabella. The assemblies of the French barons and prelates and the University of Paris resolved that males who derive their right to inheritance through their mother should be excluded. This ruling became a key point of contention in the subsequent Hundred Years War. Over the following century, French jurists adopted a clause from the 6th century Pactus Legis Salicae

In the lands of Napoleon Bonaparte's conquests, Salic law was adopted, including the French Empire, the Kingdom of Westphalia, the Kingdom of Holland and, under Napoleonic influence, the House of Bernadotte's Sweden. Other states adopted Salic primogeniture as well, including Belgium, Denmark (in 1853) and all of the eastern European monarchies except Greece, i.e. Albania, Bulgaria, Montenegro, Romania, and Serbia. During this era, Spain (in the Carlist conflicts) fought a civil war which pitted the Salic and female-line heirs of the ruling dynasty against one another for possession of the crown.

A variation of Salic primogeniture allowed the sons of women to inherit, but not women themselves, an example being the Francoist succession to the throne of Spain that was applied in 1947–1978.

Most British and French titles of nobility descend to the senior male by primogeniture, to the exclusion of females, and agnatic cadets may bear courtesy or subsidiary titles. Notable exceptions in England include the Duchy of Lancaster, which is merged with the British Crown (which has included women in inheritance since the 16th century), and the Dukedom of Marlborough, which has included women in inheritance since its establishment in 1702.

The preference for males existing in most systems of primogeniture (and in other mechanisms of hereditary succession) comes mostly from the perceived nature of the tasks and role of the monarch: A monarch most usually was, first and foremost, a military protector.

An alternative theory posits that the preference for males arose out of a desire to maximize reproductive success.

It was thought that because of a sexual double standard, in which males were able to produce illegitimate children as well as legitimate children, a son would ultimately increase one's posterity more than a daughter.

Primogeniture prevents the subdivision of estates and diminishes internal pressures to sell property (for example, if two children inherit a house and neither can afford to buy out the other's share).

In Western Europe, most younger sons of the nobility had no prospect of inheriting property, and were obliged to seek careers in the Church, in military service, or in government.

Wills often included bequests to a monastic order who would take the disinherited son.

Many of the Spanish Conquistadors were younger sons who had to make their fortune in war. In the late 17th and early 18th centuries, many younger sons of English aristocrats specifically chose to leave England for Virginia in the Colonies. Many of the early Virginians who were plantation owners were such younger sons who had left England fortuneless due to primogeniture laws. These Founding Fathers of the United States of America were nearly universally descended from the landed gentry of England.

In Japan, the Imperial chronologies include eight reigning empresses from ancient times up through the Edo period; however, their successors were most often selected from amongst the males of the paternal Imperial bloodline, which is why some conservative scholars argue that the women's reigns were temporary and that male-only succession tradition must be maintained.^[6] Japanese empresses such as Empress Genshō (680-748), who succeeded her mother the Empress Gemmei (661-721) on the throne (but only because she was a Princess of the Imperial family, daughter of Prince Kusakabe), remain the sole exceptions to this conventional argument.

The fact that the eldest son "scooped the pool" often led to ill-feeling amongst younger sons (and of course daughters).

Through marriage, estates inherited by primogeniture were combined and some nobles achieved wealth and power sufficient to pose a threat even to the crown itself.

Finally, nobles tended to complain about and resist rules of primogeniture.

In Democracy in America, Alexis de Tocqueville argues that the abolition of the laws of primogeniture and entail in the law of inheritance of private property (as opposed to inheritance of a monarchy) result in the more rapid division of land, forcing landless people to seek wealth outside the family estate in order to maintain their previous standard of living, accelerating the death of the landed aristocracy and also quickening the shift to democracy.^[7]

A case of agnatic primogeniture is exemplified in the French royal milieu, where the Salic law (attributed to the Salian Franks) forbade any inheritance of a crown through the female line. This rule was adopted to solve the dispute over the legitimate successor of Charles IV of France (Edward III of England or Philip VI of France, though the former would have a stronger claim should proximity of blood be considered). Conflict between the Salic law and the male-preferred system was also the genesis of Carlism in Spain.

The 1837 divergence of the crowns of Hanover and Great Britain upon the death of William IV of the United Kingdom resulted in the succession of his eldest surviving brother Ernest I to Hanover, while the United Kingdom was inherited by his niece, Queen Victoria, was due to the operation of semi-Salic law in Hanover and to male-preference primogeniture in the British Empire.

In 1890, the divergence of the thrones of Luxembourg and the Netherlands, both ruled by semi-Salic law, was caused by the fact that the Luxembourg line of succession went back more generations than the Dutch one.

The Luxembourg succession was ruled by the provisions of the Nassau House Treaty of 1783.

Where the succession is concerned, Luxembourg is the successor state to the Principality of (Orange-) Nassau-Dietz.

The Dutch succession only went back to King William I (1815-1840).

Therefore, Luxembourg still had agnatic heirs from another branch of the House of Nassau left to succeed, while in the Netherlands the male line starting with William I was depleted.

Since the Middle Ages, the semi-Salic principle was prevalent for the inheritance of feudal land in the Holy Roman Empire: inheritance was allowed through females when the male line expired.

Females themselves did not inherit, but their male issue could.

For example, a grandfather without sons was succeeded by his grandson, the son of his daughter, although the daughter still lived.

Likewise, an uncle without sons of his own was succeeded by his nephew, a son of his sister, even if the sister still lived.

Common in feudal Europe outside of Germany was land inheritance based on a form of primogeniture: A lord was succeeded by his eldest son but, failing sons, either by daughters or sons of daughters. In most medieval Western European feudal fiefs, females (such as daughters and sisters) were allowed to succeed, brothers failing. But usually the husband of the heiress became the real lord, assuming his wife's title with the suffix jure uxoris

In more complex medieval cases, the sometimes conflicting principles of proximity of blood and primogeniture competed, and outcomes were at times unpredictable. Proximity meant that an heir closer in degree of kinship to the lord in question was given precedence although that heir was not necessarily the heir by primogeniture.

However, primogeniture increasingly won legal cases over proximity in later centuries.

Later, when lands were strictly divided among noble families and tended to remain fixed, agnatic primogeniture became usual: succession going to the eldest son of the monarch; if the monarch had no sons, the throne would pass to the nearest male relative in the male line.

Some countries however accepted female rulers early on, so that if the monarch had no sons, the throne would pass to the eldest daughter.

For example, Queen Christina of Sweden succeeded to the throne after the death of her father, King Gustav II Adolf.

In England, primogeniture was mandatory for inheritance of land.

Until the Statute of Wills was passed in 1540, a will could control only the inheritance of personal property. Real estate (land) passed to the eldest male descendant by operation of law. The statute added a provision that a landowner could "devise" land by the use of a new device called a "testament". The rule of primogeniture in England was not changed until the Administration of Estates Act in 1925.

In law, the rule of inheritance whereby land descends to the oldest son.

Under the feudal system of medieval Europe, primogeniture generally governed the inheritance of land held in military tenure (see knight). The effect of this rule was to keep the father's land for the support of the son who rendered the required military service. When feudalism declined and the payment of a tax was substituted for military service, the need for primogeniture disappeared. In England, consequently, there was enacted the Statute of Wills (1540), which permitted the oldest son to be entirely cut off from inheriting, and in the 17th century military tenure was abolished; primogeniture is, nevertheless, still customary in England. In the United States primogeniture never became widely established.

Another variation on agnatic primogeniture is the so-called semi-Salic law, or "agnatic-cognatic primogeniture", which allows women to succeed only at the extinction of all the male descendants in the male line.^[8] Such were the cases of Bourbon Spain until 1833 and the dominions of Austria-Hungary, as well as most realms within the former Holy Roman Empire, i.e. most German monarchies. This was also the law of Russia under the Pauline Laws of 1797 and of Luxembourg until equal primogeniture was introduced on 20 June 2011.

There are various versions of semi-Salic law also, although in all forms women do not succeed by application of the same kind of primogeniture as was in effect among males in the family.

Rather, the female who is nearest in kinship to the last male monarch of the family inherits, even if another female agnate of the dynasty is senior by primogeniture.

Among sisters (and the lines of descendants issuing from them), the elder are preferred to the younger.

In reckoning consanguinity or proximity of blood the dynasty's house law defines who among female relatives is "nearest" to the last male.

Under uterine primogeniture, succession to the throne or other property is passed to the male most closely related to the previous titleholder through female kinship.^[5] A male may also inherit a right of succession through a female ancestor or spouse, to the exclusion of any female relative who might be older or of nearer proximity of blood (see above for Spain's mid-twentieth century dynastic succession law). In such cases, inheritance depends on uterine kinship,^[5] so a king would typically be succeeded by his sister's son. This particular system of inheritance applied to the thrones of the Picts of Northern Britain and the Etruscans of Italy. Some kingdoms and ethnic groups in Africa follow the same practice. This usage may stem in part from the certainty of the relationship to the previous king and kings: sons and daughters of a sister are his relations (mater semper certa est), even if they do not have the same father.

Matrilineal primogeniture, or female-preference uterine primogeniture, is a form of succession practised in some societies in which the eldest female child inherits the throne, to the total exclusion of males. The order of succession to the position of the Rain Queen is an example in an African culture of matrilineal primogeniture: not only is dynastic descent reckoned through the female line, but only females are eligible to inherit.

In Christian Europe, the Catholic Church originally had a monopoly on the authority to sanction marriage. It forbade polygamy and taught that divorce was an impossibility per se, as it still does. Consequently, in Europe, it was very difficult to ensure succession solely by direct male descendants or even direct male or female progeny. In Islamic and Asian cultures, religious officials and customs either sanctioned polygyny, use of consorts, or both, or they had no authority of marriage; monarchs could consequently ensure sufficient numbers of male offspring to assure succession. In such cultures, female heads of state were rare.

The earliest account of primogeniture to be known widely in modern times is that of Isaac's sons Esau, who was born first,^[9] and Jacob, who was born second.^[10] Esau was entitled to the "birthright" (bekhorah בְּכוֹרָה), but he sold the right to Jacob for a mess of pottage, i. e. a small amount of food.^[11] Although the veracity of this account is not corroborated by other sources, its widespread acceptance demonstrates that primogeniture was sufficiently common in the Middle East for the account to seem plausible to the people living there prior to the Roman Empire. In the Bible a woman's right and obligation to inherit property in the absence of a male heir in the family was established by the Daughters of Zelophehad in Numbers 27.

During the Roman Empire, Roman law governed much of Europe, and the laws pertaining to inheritance made no distinction between the oldest or youngest, male or female, if the decedent died intestate.^[12] Although admission to the two highest ordines (orders), i. e. the senators and equestrians, potentially brought lifelong privileges that the next generation could inherit, the principle of inherited rank in general was little used.^[13] Rather, Roman aristocracy was based on competition, and a Roman family could not maintain its position in the ordines merely by hereditary succession or title to land.^[14] Although the eldest son typically carried his father's name in some form, he was expected to construct his own career based on competence as an administrator or general and on remaining in favor with the emperor and his council at court.^[15]The%20Political%20Economy%20of%20the%20Roman%20Empir]]Other than meeting requirements for personal wealth, the qualifications for belonging to the senatorial or equestrian orders varied from generation to generation, and in the later Empire, the dignitas rank was refined further with additional titles, such as vir illustris, that were not inherited.^[16]

Most Roman emperors indicated their choice of successor, usually a close family member or adopted heir, and the presumption that the eldest or even a natural son would inherit was not enshrined. The death of an emperor led to a critical period of uncertainty and crisis. In theory, the Senate was entitled to choose the new emperor, but did so mindful of acclamation by the army or the Praetorian Guard.^[17] Thus, neither an emperor nor his heir had an inherent "right" to rule, and did so through military power and the Senate's symbolic consent.

The law of primogeniture in Europe has its origins in Medieval Europe; which due to the feudal system necessitated that the estates of land-owning feudal lords be kept as large and united as possible to maintain social stability as well as the wealth, power and social standing of their families.^[12]

Adam Smith, in his book An Inquiry into the Nature and Causes of the Wealth of Nations

A case of agnatic primogeniture is exemplified in the French royal milieu, where the Salic Law (attributed to the Salian Franks) forbade any inheritance of a crown through the female line. This rule was adopted to solve the dispute over the legitimate successor of John I of France, the short-lived son of deceased Louis X of France in favour of Philip V of France (brother of Louis and uncle of John) over Joan II of Navarre (daughter of Louis and sister of John), the Estates-General of 1317 ruling that "Women do not succeed the kingdom of France". In 1328, it was further elaborated, with the statement that "Women cannot transmit a right which they do not possess", to solve the dispute over the legitimate successor of Philip V's brother Charles IV of France (Edward III of England or Philip VI of France), though the former would have a stronger claim should proximity of blood be considered, which had never been the case in France since 987, instead as well of both agnatic-cognatic primogeniture or male-preference cognatic primogeniture and the resulting heirs. This dispute was among the factors behind the Hundred Years' War, which broke out in 1337.

Conflict between the Salic law and the male-preferred system was also the genesis of Carlism in Spain and Miguelism in Portugal.

The crowns of Hanover and Great Britain, which had been in personal union since 1714, were separated in 1837 upon the death of King William IV: his niece Victoria inherited the British crown under male-preference primogeniture but, because of semi-Salic law, was not the heir to that of Hanover, which passed to William's eldest surviving brother, Ernest Augustus, King of Hanover.

The divergence in the late 19th century of the thrones of Luxembourg and the Netherlands, both subject to semi-Salic law, resulted from the fact that the Luxembourg line of succession went back more generations than did the Dutch line.

The Luxembourg succession was set by the Nassau House Treaty of 1783, which declared each prince of the House of Nassau to be a potential heir to the territories of every branch of the dynasty. Insofar as the succession is concerned, the Grand Duchy of Luxembourg is the successor state to the Principality of (Orange-)Nassau-Dietz, which was given in exchange to William VI of Nassau, Prince of Orange in 1813. Succession to the new Kingdom of the Netherlands was recognised by the Congress of Vienna in 1815 as belonging exclusively to the descendants of Prince William VI, who became King William I of the Netherlands. In 1890, William I's agnatic line of male descendants died out, leaving the Netherlands to his female descendant Queen Wilhelmina, whereas Luxembourg still had an agnatic heir from a distant branch of the dynasty left to succeed; ex-Duke Adolf of Nassau, who became reigning Grand Duke, thus ending the personal union of the Netherlands and Luxembourg.

Since the Middle Ages, the semi-Salic principle was prevalent for the inheritance of feudal land in the Holy Roman Empire: inheritance was allowed through females when the male line expired.

Females themselves did not inherit, but their male issue could.

For example, a grandfather without sons was succeeded by his grandson, the son of his daughter, although the daughter still lived.

Likewise, an uncle without sons of his own was succeeded by his nephew, a son of his sister, even if the sister still lived.

Common in feudal Europe outside of Germany was land inheritance based on a form of primogeniture: A lord was succeeded by his eldest son but, failing sons, either by daughters or sons of daughters. In most medieval Western European feudal fiefs, females (such as daughters and sisters) were allowed to succeed, brothers failing. But usually the husband of the heiress became the real lord, assuming his wife's title (jure uxoris

In more complex medieval cases, the sometimes conflicting principles of proximity of blood and primogeniture competed, and outcomes were at times unpredictable. Proximity meant that an heir closer in degree of kinship to the lord in question was given precedence although that heir was not necessarily the heir by primogeniture.

However, primogeniture increasingly won legal cases over proximity in later centuries.

Later, when lands were strictly divided among noble families and tended to remain fixed, agnatic primogeniture (practically the same as Salic Law) became usual: succession going to the eldest son of the monarch; if the monarch had no sons, the throne would pass to the nearest male relative in the male line.

Some countries, however, accepted female rulers early on, so that if the monarch had no sons, the throne would pass to the eldest daughter.

For example, in 1632 Christina, Queen of Sweden succeeded to the throne after the death of her father, King Gustav II Adolf.

In England, primogeniture was mandatory for inheritance of land.

Until the Statute of Wills was passed in 1540, a will could control only the inheritance of personal property. Real estate (land) passed to the eldest male descendant by operation of law. The statute added a provision that a landowner could "devise" land by the use of a new device called a "testament". The rule of primogeniture in England was not changed until the Administration of Estates Act in 1925. In law, primogeniture is the rule of inheritance whereby land descends to the oldest son. Under the feudal system of medieval Europe, primogeniture generally governed the inheritance of land held in military tenure (see knight). The effect of this rule was to keep the father's land for the support of the son who rendered the required military service. When feudalism declined and the payment of a tax was substituted for military service, the need for primogeniture disappeared. In England, consequently, there was enacted the Statute of Wills (1540), which permitted the oldest son to be entirely cut off from inheriting, and in the 17th century military tenure was abolished; primogeniture is, nevertheless, still customary in England.

In British North America, the colonies followed English primogeniture laws. Carole Shammas argues that issues of primogeniture, dower, curtesy, strict family settlements in equity, collateral kin, and unilateral division of real and personal property were fully developed in the colonial courts. The Americans differed little from English policies regarding the status of widow, widower, and lineal descendants.^[19] The primogeniture laws were repealed at the time of the American Revolution. Thomas Jefferson took the lead in repealing the law in Virginia, where nearly three-fourths of Tidewater land and perhaps a majority of western lands were entailed.^[20] Canada had the same law but repealed it in 1851.^[21]

When Winston Churchill and Franklin Roosevelt met at Placentia Bay in August 1941, the latter said he couldn't understand the British aristocracy's concept of primogeniture, and he intended to divide his estate equally between his five children; Churchill explained that an equal distribution was nicknamed the “Spanish Curse” by the British upper classes: “We give everything to the eldest and the others strive to duplicate it and found empires. While the oldest, having it all, marries for beauty. Which accounts, Mr President, for my good looks”. But as Churchill's father was a younger son, there may have been more modesty than mock-vanity than Roosevelt realised.^[22]

In 2006, King Juan Carlos I of Spain decreed a reform of the succession to noble titles from male-preference primogeniture to absolute primogeniture.^[23][24]

Since 2013, there has been a revived movement to reform hereditary peerage inheritance law for equal primogeniture.

The Equality (Titles) Bill and its successive legislation have been referred to as the "Downton law" in reference to the British television drama Downton Abbey where the earl's eldest daughter is unable to inherit the family seat because it is entailed and can be passed only to a male heir.^[25]