The Norman Conquest began major French influence on English in 1066. William, Duke of Normandy, defeated Harold Godwinson at the Battle of Hastings and became king of England later that year.
After the conquest, Norman French became the language of the royal court, aristocracy, administration, law, and parts of the church. Most ordinary English people continued speaking varieties of Old English, so England developed a long period of social and linguistic bilingualism rather than an instant replacement of English.
French influence reshaped English vocabulary, especially in government, law, religion, cuisine, and social life. Words such as “court,” “judge,” “government,” “beef,” and “mutton” entered English through French or Anglo-Norman usage. French scribes also influenced spelling conventions, including forms such as “qu,” “ou,” and “ch.”
The change was gradual. English eventually re-emerged as the dominant language of public life, but centuries of contact helped produce Middle English and left English with a large Romance vocabulary alongside its Germanic core.