Agnatic Seniority

Agnatic seniority is a patrilineal principle of inheritance where the order of succession to the throne prefers the monarch's younger brother over the monarch's own sons. A monarch's children (the next generation) succeed only after the males of the elder generation have all been exhausted. Agnatic seniority essentially excludes females of the dynasty and their descendants from the succession. Contrast agnatic primogeniture, where the king's sons stand higher in succession than his brothers.

In hereditary monarchies, particularly in more ancient times, seniority was a much-used principle of order of succession. The Ottoman Empire evolved from an elective succession (following the principle of agnatic seniority) to a succession inherited by the law of agnatic seniority.

In succession based on rotation (close to seniority), all (male) members of the dynasty were entitled to the monarchy, in principle. However, this tends to lead to situations where there is no clear rule to determine who is the next monarch.

Brothers succeeding each other as a system leads quickly, particularly in the following generations, to complex patterns and also to disputes between branches which have formed within the monarchical house. Monarchs had collateral relatives, some of whom were rather distant cousins, who were often as entitled to succeed as the monarch himself. Either one branch obtained sufficient control over others (often by force), the rival branches arrived at a balance (such as the succession becoming rotational), or the inheritance was somehow partitioned.

Succession based on agnatic seniority or rotation was often limited to those princes who were sons of an earlier reigning monarch. Thus a son of a king had a higher claim than a son of a prince. In some cases, distinctions were even made based on whether the claimant was born to a monarch who reigned at the time of birth (porphyrogeniture).

This limit was practical, as otherwise the number of rivals would be overwhelming. However, it usually left more than one rival who too often waged civil war against each other. In other cases, the eligible branches of dynasty went extinct in the male line (no surviving sons), in which situation the limit was problematic.

Sons of princes who did not live long enough to succeed to the throne were of course unsatisfied with such limits. This led to interpretation problems - what if a claimant's father was a rightful monarch, but not recognized by everyone? or by no one (did not rule at all in fact)? The cases were further complicated by co-reigning monarchs, but this was often a practical solution to a controversial succession.

Agnatic seniority tends in the long run to favor a sort of ultimogeniture, because princes born in a certain generation to the most junior lines tend to be more likely alive at the demise of the predecessor (the last of the immediately preceding generation). In a situation where representatives from any later generation are not allowed to succeed until the last ones of the earlier generation die, plenty of dynasts, usually from more senior branches, will die before their turn on the throne (no wonder they would prefer primogeniture). This tendency is one of the causes of disputed successions: some desire to succeed before they die, and plead the seniority or better blood of their branch. This is further exacerbated if a dynast is not allowed to succeed in case his father was not regnant (or is regarded just as a spare, eligible to succeed only after all those males whose fathers were regnant) - senior branches will with high likelihood sooner or later lose their places in succession. Agnatic seniority tends to favour boys who are born to fathers in their old age.

Succession within one family based on seniority was often a device to control an elective monarchy. Those two forms of monarchy (agnatic seniority and elective monarchy) were mostly used in the same centuries. Many kingdoms were officially elective long into historical times (though the election usually, or always, fell to family of the deceased monarch).

The preference for males which exists in most systems of hereditary succession came mostly from the perceived nature of the role of the monarch:

• Tribal chiefs (proto-monarchs) were required to personally participate in violent activities such as war, duels, and raiding expeditions.

• His income was dependent on the "protection money" or corvee labour collected from those people he was supposed to protect from violence, both from outside (war) and from within (crime). Of course, the collection of these funds or services often required the threat or actual use of force by the monarch, but more politely labeled "taxes" and "duties". These forms of revenue-collecting are, of course, also present in non-monarchical systems.

• It was very useful, or even required, that the monarch be a warrior and a military commander. Warriors (almost always males) often would only accept other males as their commanders.

• Additionally, in some monarchies, the monarch held a certain mystical, almost priestly, position. That role, depending on the tradition in question, was often denied to females. In the French monarchy, one of the official explanations for the Salic Law was that the monarch was obliged to use certain sacred instruments, which females were forbidden even to touch.

In earlier centuries, perhaps in every second or every third generation on average, the male line often became extinct and females were needed to trace the line of succession. During this period, male lines tended to become extinct relatively quickly, usually due to violent death. Therefore, "pure" agnatic succession was impossible to maintain, and frequent exceptions were made - eligibility being granted to the eldest sons of sisters or other female relatives of the monarch.

The fully agnatic succession also did not serve the interests of individual monarchs who favoured close female relatives and their descendants over very distant male relatives.

In the later Middle Ages, violence directly involving the monarch and his heirs became less of a factor, as they gradually decreased their personal participation in combat. Sons were much more likely to survive to adulthood and to marry than in previous centuries, when many noble families lost adolescent sons to constant warfare. In addition, the living conditions and nutrition of the nobility improved, leading to fewer miscarriages and decreased infant and childhood mortality. Daughters were therefore needed less and less to trace succession.

In many cultures, surnames are agnatically determined.