After the Norman conquest, the Normans began to fight not only the Saxons, but the Welsh, the Scottish, and the Irish. They began to fight each other too. It's called "feudalism". Many Saxon nobles fled England after the Normans took over. They even became the imperial guard of the Byzantine Emperor, the Varangian Guard. Most of the Saxon common people who remained merely found themself ruled by a Norman Lord other than a Saxon Lord. They were all Christians, and priests were priests no matter the language since all priests spoke Latin.

Castles were still in use in the English Civil War in the 17th Century, and sheltering in one all depended whether you were Puritan, or some kind of Papist.