“In this kingdom, as is well known, a king is constituted not by the wishes of the people or by election or by the right of war but by the propagation of blood.” So wrote Margaret of Burgundy, the sister of Edward IV and Richard III of England, in the 15th century – and it’s hard to argue with her logic.


Few European countries have kings or queens today, only seven in all. But in the long span of European history, this is only a recent development. In 1900, every European state – barring France and Switzerland – was a monarchy. As for medieval Europe, it was, almost without exception, ruled by a patchwork of royal and imperial families. As a result, politics at the highest level was dynastic, revolving around the births, marriages and deaths of these families – not to mention their conflicts and alliances. Transmission of power was not a matter of elections but of biology.

Some of these dynasties were extremely successful at propagating their blood. Hugh Capet, who became king of the Franks in 987, was the ancestor in the direct male line of every French king down to 1848, nearly nine centuries later. Other medieval dynasties could not compete with this, but often held on to their thrones for several centuries.

But there are also examples of medieval kings – sometimes highly successful ones – who were the only members of their family to hold the throne. Matthias Corvinus, king of Hungary from 1458–90, was a great patron of Renaissance culture, yet was unable to secure the succession of his illegitimate son. The same is true of John Balliol, king of Scots from 1292–96, although his son Edward Balliol did make a prolonged effort to take back his father’s throne in the following century. And then there’s Harold Godwinson, whose sons were unable to reverse the defeat at the battle of Hastings in 1066, despite invading England two years later.

The three things every dynasty needs

A successful dynasty needed to do three things. The first was to defend itself against rival dynasties, something John Balliol and Harold Godwinson failed to do. The second, and fundamental, task was to ensure biological survival. The third was to find ways of containing and controlling competition within the dynasty.

It is clear that there might be a contradiction between these two last requirements. For instance, a king might seek to secure his dynasty by having large numbers of sons by various women. This was a practice common among Irish kings, a notable example being Toirdelbach Ua Conchobair (Turlough O’Connor), king of Connacht (1106–56), who had 22 sons by at least six partners. This did indeed mean that Connacht (or parts of it) remained under the rule of O’Connors down to the Tudor period but it also meant there were always many competing lines of the dynasty. Kings of Connacht were killed more often by brothers or cousins than by the English invaders.

Not many medieval kings had 22 sons. Most of them, especially after the early Middle Ages, accepted the concept of marriage as defined by the church: one wife at a time. Because of this, choice of a bride for a king or for the heir to the throne became a central obsession of dynastic politics, often involving negotiations about the future marriage of babies, or even, on rare occasions, their actual marriage. Henry, son of Henry II of England, was married to Margaret, daughter of the king of France, when he was five and she was two. There was contemporary criticism of this marriage of “little children still wailing in the cradle”, but it brought Henry II the important territory of the Norman Vexin as the bride’s dowry.

One fundamental decision that needed to be made about a dynasty’s marriage policy was whether a bride should be sought from a foreign royal family or from the local aristocracy. Both policies had their advantages and disadvantages, which were argued out. Indeed, in a later dynastic state, 18th-century Russia, a writer devised a fictional dialogue between a champion of the view that the tsar should marry a foreign princess and another who claimed he should marry one of his own subjects. The former, we’re told, presented 40 arguments for his case, but the latter alleged he had 400!

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Suitors were offered a choice of sisters, and if one died, a younger sibling would be substituted

Marriage to a high-born native lady allied the ruler to a noble family, which could be a source of strength, but it might also upset the balance of aristocratic politics, as occurred in the case of Edward IV of England. His marriage to Elizabeth Woodville in 1464 was the first between an English king and an English woman since 1066. But the subsequent promotion and enrichment of Woodville’s relatives alienated many of Edward’s own aristocratic supporters and led to his (temporary) dethronement in 1470.

Marriage to foreign princesses was also a way of creating alliances. The dynastic rather than personal nature of such transactions comes out most clearly when prospective husbands were offered a choice of sisters. It was also evident in marriage treaties that specified that, if one of the children involved should die, a younger sibling would be substituted.

Bonds between dynasties were at stake here, not the emotions of individuals. And these marriages often involved the bride going from one cultural world to another, perhaps even having to adopt a different name to fit in with the new environment. One Byzantine bride who came to the west to marry was criticised for her fancy ways, such as eating with a fork. The German aristocrat Berta, who went the other way to marry into the Byzantine imperial family, had to change her name to the Greek Irene but was still derided for not wearing eye makeup.

The quest for sons

The purpose of all these endless marriage negotiations was to achieve the essential dynastic goal: the birth of a child, or, to be more precise in this highly patriarchal world, the birth of a son. A woman’s fertility could not be known beforehand, though sometimes efforts were made. When French envoys came to Aragon in 1322 to examine the king’s daughter as a potential bride for the king of France, they were instructed “to see her naked breast”, since this would indicate her ability to have children, “which the king much desires” (she apparently failed this test).

Royal courts would always be obsessed with the wait for sons to be born. After long years of marriage without a pregnancy, or after giving birth only to girls, a queen would find her position vulnerable, and talk would begin about ways of getting rid of her. The church did not recognise divorce in the modern sense: the termination of a legal marriage. However, it did countenance annulment, that is, the declaration that that the union had never been a proper marriage at all, on various grounds, especially because the parties were too closely related. In the dense intermarried network of medieval royalty, such relationships (‘prohibited degrees’) were not too difficult to discover.

A famous example, with great political consequences, was the annulment of the marriage of Louis VII of France and Eleanor of Aquitaine, who had borne only daughters in the 15 years of their marriage. She was now available to marry again, was quickly sought out by the young Henry of Anjou and married him within months. She brought with her the huge duchy of Aquitaine, which was her inheritance, and gave him eight children including five sons. Perhaps if Louis had waited, she would have brought him sons, and he certainly would have kept Aquitaine out of the hands of his great rival, Henry, who became Henry II of England. The central role of the female body in this tale of high politics scarcely needs underlining.

Louis VII provides a good example of the way an entire reign could be dominated by the pursuit of a male heir. He married Eleanor just before his father’s death in 1137 and had the marriage annulled in 1152. In 1153 or early 1154 he married again, to Constance, daughter of the king of Castile. Like Eleanor she gave him two daughters, dying during the birth of the second, in the autumn of 1160. Within a matter of weeks, Louis married for the third time, to Adela of Champagne, member of a great French noble family. By New Year 1165 it was clear that Adela was pregnant and tension mounted as she drew near to term in the summer of that year. Paris held its breath. A young student expressed the mood in verse:

It was night and the queen was in labour in this famous childbirth;

the city beseeches you about this, O Christ, with wakeful prayer.

The eager wishes of the city beg that it be male; the tearful court asks God for a male.

It was a male. Twenty-eight years into his reign, Louis VII finally had his son, who became Philip Augustus, one of the most successful French monarchs of the Middle Ages. The Capetian dynasty had hung on by a thread, and went on to pass the French throne directly from father to son for another six generations.

What happens when a king dies without a son?

The death of a king without a son always meant political crisis. What happened in Aragon in 1134 shows this clearly. In that year Alfonso ‘the Battler’, who had been king of Aragon for 30 years, died from wounds received in fighting the Spanish Muslims. He left no children. Alfonso deserved his nickname: he had conquered the important Muslim city of Zaragoza and was respected as a warrior by his Muslim enemies, although they were bemused by the fact that he did not sleep with the daughters of the Muslim chiefs he captured. He had had a short and childless marriage and his only close male relative, his brother, had become a monk. In these circumstances, Alfonso made the unusual decision to bequeath his kingdom to the crusading Orders – the Templars, Hospitallers and Order of the Holy Sepulchre.

The dead king’s brother was hauled out of a monastery, and only allowed to return once he’d fathered an heir

If Alfonso’s will had been carried out, Aragon would have become the first state run by crusading Orders, of the type later exemplified by the Teutonic Knights in Prussia and the Hospitallers in Rhodes. However, the nobility of Aragon were not prepared for this to happen and took extraordinary steps to secure the survival of the native dynasty. Alfonso’s brother, Ramiro the monk, was hauled out of his monastery, married to a noble French lady and only allowed to return to his monastic life after she had given birth to a child, a daughter named Petronilla. Even those who thought such proceedings were wrong understood the desire of the Aragonese to perpetuate ‘the royal seed’.

Petronilla thus became queen of Aragon at the age of one. She would obviously need a protector and so was engaged to the powerful count of Barcelona, whose lands bordered Aragon. He was 23 years her senior and would have a long wait before sexual relations could begin. But, as she approached her 15th birthday, Petronilla became pregnant and awaited the birth in her husband’s city of Barcelona, where, on 4 April 1152, she issued a document with no parallel. It began: “I, Petronilla, queen of Aragon, lying and labouring in childbirth at Barcelona…” She then made provision for the child that was imminently expected, whether it is a boy that “is to proceed from my womb, by God’s will”, or “if a daughter should proceed from my womb”, and donated 2,000 gold coins to the churches of Aragon and Barcelona to pray for her. She gave birth to a healthy boy who became king after her. The ‘royal seed’ of Aragon was thus preserved.

The Aragonese had been willing to accept rule by a queen from the native royal family in preference to other alternatives. But Petronilla was not the first female sovereign in medieval Europe. There had already been three ruling empresses in Byzantium, although none of them had been in power for long, and Aragon’s neighbour, the kingdom of Leon and Castile, was ruled by Queen Urraca from 1109 to 1126. At the time of the Aragonese crisis of 1134 the ruler of the kingdom of Jerusalem, a European colony, was a woman, Queen Melisende. There were at least 27 female sovereigns in medieval Europe (including Jerusalem). While this patriarchal society preferred the rule of men, often justified on military grounds, women could be recognised as the bearers of dynastic claims if kings lacked sons.

Jealous siblings and family feuds

But if the problem of dynastic continuity was solved by fertile marriages and the birth of sons, this left the other problem that dynasties faced: that of containing conflict and competition. Royal sons, including younger ones, were brought up to exercise command, to fight on horseback with lethal weapons, and to glory in their high blood. These proud young men had a high sense of their dignity and resented restrictions and limitations.

Even if the eldest was recognised as heir, perhaps being crowned in his father’s lifetime, he might still think his father was taking a long time to die. Louis the Dauphin, son of Charles VII of France, “had, for a long time, desired to reign and to have the crown on his head”, when, in 1456, he fled to the court of his father’s enemy, the Duke of Burgundy. Louis didn’t meet Charles for the last 14 years of the king’s life – though that didn’t stop him succeeding to the French throne five years after his flight.

Younger brothers also posed a threat to family unity, sometimes refusing to acquiesce in the privileged status of the eldest. In some dynastic systems their rights were recognised by a division of the kingdom on the old king’s death. The giant Frankish kingdom was frequently divided between brothers or cousins in the early Middle Ages, although such divisions became rare after AD 1000.

Some of the most successful dynasties found ways of satisfying the claims of younger brothers and of harnessing their energies, as Louis IX of France (St Louis) did. His three brothers served him well, on the whole, all accompanying him on crusade, in which one died and one stood hostage as security for the king’s ransom when he was captured.

All three brothers had been provided with huge lordships in France – which helps explain their loyalty. But this method had great dangers of its own. These apanages, large territorial endowments for younger brothers, might drift permanently out of the king’s control. The Burgundian domains, which almost became a separate kingdom, started out in just this way.

Dynasties thus steered a perilous course between the threat of biological extinction and the chaos of conflict within the family.

There were other political systems in medieval Europe. Iceland and Venice, two places about as different as is possible to be, were both republics. The Holy Roman Empire, comprising Germany and north Italy, was always elective in theory, and elective in reality from 1254 to 1438, after which the Habsburgs established a monopoly of the imperial title.

But it was dynastic politics that left the deepest mark on Europe, a mark that can be seen to this day, both in the states that arose from dynastic unions, such as Spain, or those that arose from dynastic fission. France and Germany did not exist in the early Middle Ages and are the result of a family division between Charlemagne’s grandsons. There was dispute over their boundaries, an argument that was still going on in the 20th century. Who would believe that some makeshift dynastic arrangement of the ninth century would be etched permanently on the map of Europe, and that young men might die for that line in 1870 or 1914, a thousand years after it was devised? The family politics of medieval Europe were, in a sense, family squabbles writ large, but sometimes they were writ very large indeed.

Robert Bartlett is Bishop Wardlaw professor of medieval history emeritus at the University of St Andrews, and the author of Blood Royal: Dynastic Politics in Medieval Europe (Cambridge University Press, 2021)


This article was first published in the August 2020 edition of BBC History Magazine