In the centuries that followed the Battle of Hastings, all the levers of power were taken over by William, his successors, and the descendants of the Norman knights that had fought in 1066. And this had linguistic repercussions.
A scene in the novel Ivanhoe by Walter Scott describes the situation around 100 years after the Norman Conquest, by which time the old English language, predominately Germanic, had started to change irrevocably. Scott’s character, Wamba the jester, jokes that the animals that are being herded in the fields by the downtrodden serfs all have Saxon names: cow, calf, swine, sheep. As soon as these same animals are put on the table to be eaten by the Norman overlords, the names become French: beef, veal, pork, mutton. Thus, a century after the Battle of Hastings, the basic words in English remained Saxon, but there had been a huge influx of Norman French. This phenomenon is with us to this day and is a gift to English-speakers who wish to learn foreign languages.
Take these word pairs and near-synonyms: freedom, liberty; friendship, amity; town, city; drink, beverage; white, pale; red, rubicund; green, verdant; naked, nude; childish, puerile. The first in each pair is Germanic, the second Latin-derived or Romance; the first is an essential word, the second merely useful or interesting; the first speaks to our heart, the second to our mind. Why?
As Old English already had words for all the basic concepts, the imported French and Latin equivalents came to have a more restricted use. Interestingly, the English word soul is Germanic, whereas spirit is derived from French. That encapsulates the fundamental character of English, one we can use to improve our language learning: it has a Germanic soul and a Latin mind. What we feel is Germanic, what we analyse is Latin.