Polycarp (may I call you ManyFish?)
I’m afraid I disagree with your comments about entail governing the succession of titles:
I think you’re confusing the concept of primogeniture, which governed the succession of titles and land in the feudal period, with the common law concept of an entail, which was a legal estate in land that evolved in the 13th and 14th century. As well, I disagree with your comments about the power of a land-holder to dispose of property by a will, at least in the feudal period, because land could not at that time be the subject of a will.
Under true feudalism, a land-holder did not “own” land, at least by modern understandings of the term. He held the land from his lord, in return for an obligation of military service to the lord. In the early beginnings of feudalism, this was purely a personal relationship between the lord and the land-holder. Upon the death of the land-holder the land reverted to the lord, who could then re-assign it to someone else.
Over time, the custom arose that upon the death of the land-holder, the land-holder’s heir had a right to have the lord re-assign the land to him. By custom, the heir was the eldest surviving son of the deceased land-holder - the principle of primogeniture. Thus, the example I gave of Robert succeeding William the Conqueror as Duke of Normandy. William held the Duchy as a vassal of the King of France, and by the feudal custom it went to the eldest surviving son, Robert, under the terms of that feudal grant.
If William had acquired some other possession by conquest, one that had an overlord, in theory the disposition of that property on William’s death would have had to be by the consent of the overlord, a point made by Akatsukami. (I say in theory, because the strength of the feudal ties varied considerably from region to region.) Since the overlord’s consent was required, this was not a will. If the overlord accepted the arrangement, the second son would do homage to the overlord for the land.
What was unique about William’s position vis-a-vis England was that he had conquered a completely independant kingdom, with no feudal overlord. Thus he was completely free to dispose of it as he pleased on his death, subject only to practical political constraints such as the Witan (no longer very effective) and the respective abilities of his sons.
So, what about the entail? This arose after the period of classic feudalism. In England, fedualism gradually evolved, with feudal tenures coming to look more and more what we would today call propery rights in the land. As feudal theory receded, land-holders began to look for ways to make temporary dispostions of their land within the family, for example to give land to a son during the father’s lifetime, but without alienating it entirely.
The statute known as De Donis Conditionalibus, 13 Edw. I, c. 1, enacted in 1285, was one response to this trend. De Donis dealt with conditional transfers of land. It did not itself create the entail as a separate legal interest in land, but in an important court case in 1312 (Yearbook of 5 Edw. II), the Court of Common Pleas interpreted it in a way that the entail became an interest in land, mid-way between an estate in fee simple and a life interest. This was the beginning of the entail in English law. It was only from this point on that individual parcels of land could be entailed.
Primogeniture continues to govern the descent of titles in the U.K. today. Whether a particular parcel of land is entailed depends on the history of dispositions with respect to that land. One key difference between primogeniture and the modern entail is that an entail can be ended, by the agreement of the various interested parties, and the land converted back to a fee simple. That can’t be done with a title.
(The above is a rough paraphrase/precis from Milsom, “Historical Foundations of the Common Law,” 2nd ed., 1981.)