There William the Conqueror finished his work. There not only every
baron, but every baron's free vassal or tenant, from Cornwall to the
Scottish borders, bowed before the King and swore to be "his man"
(S86). By that act England was made one. By it, it was settled that
every landholder in the realm, of whatever condition, was bound first
of all to fight in behalf of the Crown, even if in so doing he had to
fight against his own lord.[1] The barons broke this oath in the next
reign (S130), but the moral obligation to keep it still remained
binding.
[1] See SS86, 150; see also the Constitutional Summary in the
Appendix, p. v, S6. Even if the men should disregard this oath of
allegiance, they could not help feeling that the principle it
represented had been acknowledged by them.