The Normans were a people that began as Norse invaders of the British Isles, then lost their foot-hold their to the Anglo-Saxons, and left for the northern shores of Gaul, which in time became Normandy (land of the Norse men - thus “Normans”), where they built up their duchy there, under permission of the Frankish kings. About 150 years later, under William and by then a mixture of Norse and Frankish culture and sentiment, they return to retake England as part of a royal succession contest.
What has always been interesting to me, is that lost (rarely discussed) in all the history of how the Normans were in England, lost out to the Anglo-Saxons, resettled in Normandy, and returned from Normandy to conquer England, is how they lost Normandy itself, as eventually Norman power in Normandy was lost to the Frankish Kings.
Not understanding what took place in Normandy itself, you’d think that “Norman England” after 1066 would reign in Normandy itself as well, and continue to. But that was not the case.