What happened after the Battle of Hastings?

The main thing that changed was that French became the language of the nobility, and the poorer people were despised and spit upon for speaking English. This had a substantial impact on how the English language looks today. It also led to some wonderful popular phrases that were made up by English speakers who did not understand French. The best known is the name of the London square called "Elephant and Castle." The square had a statue of the Infanta of Castille on it (called "l'Infante de Castille" in French). The non-French-speaking locals came up with the best phonetic fit: Elephant and Castle.