In England we have but one law of succession, which rules through the whole land.

In France it is different.

There the law of succession depends entirely upon the custom of the county, dukedom, or lordship, which is further affected both by the form of grant by which the territory was conveyed to its first feudal possessors and by the mode in which the province had been acquired by the kings of France.

This is important, as upon these circumstances alone it depended whether the son or the granddaughter of Arthur II should inherit the dukedom.
"Joan claimed the duchy as the daughter of the elder brother.

The Salic law of France, which barred females from the right of succession, and in virtue of which Philip of Valois succeeded to the throne instead of King Edward, certainly did not obtain in Brittany.