The Welsh Marches
The history of England between Conquest leading up to Magna Carta can be a little difficult to explain what went on and why.
My contention all along was that there must have been divided loyalties with respect to the barons that have lands in both Normandy and the newly "conqurored" England. Up until King John and his loss of Normandy at Les Andelys in 1204, the Barons had to make a choice with regard to their loyalties.
Whereas the French defeated King John at the Château Gaillard to the forces of Philip Augustus (Philip II of France), Normandy came under French rule. The English made many attempts to re-take their French lands but Charles VII of France finally defeated the English in 1449. This effectively ended The Hundred Years War, or at least was close to it.
Marcher Lords
Philip de Braose became a Marcher Lord 1212????