The Effect of 1066 Norman Invasion on the English Language.
The English language that is spoken today is the direct result of 1066 and the Norman Conquest. Modern English is vastly different from that spoken by the English prior to the Conquest, both in its word-hoard and its grammar.By 1100 English had changed sufficiently to be classed as a 'new' version of English, descended from, but quite different to, Old English.
So, how had the changes come about? When the Norse had settled in England they brought with them a language that was from the same linguistic family, and indeed enabled them to be understood by their English neighbours. The culture was also similar, not surprising considering that the original English had come from Scania, Denmark and the North Sea coast bordering Denmark. In addition the new comers supplemented, rather than replaced, both the aristocracy and the commons. As a result assimilation was very quick and easy even before the fighting stopped. The Normans brought with them an alien culture and language. Add to this their social status as the new ruling class, and it is no shock to find that assimilation was slower, and the new society and language that emerged was so radically changed from that which they found when they arrived uninvited in 1066.
English, which had been a written language since the conversion to Christianity, was rapidly dropped as the language for royal and legal charters and proclamations, not reappearing until Simon De Montfort's Parliament issued the Provisions of Oxford in 1258. The replacement language was usually Latin, though often duplicated in French. French was the language of the royal court, the legal system and the church. The use of French was reinforced by the fact that many of the new aristocracy and religious houses had extensive holdings in France. This state of affairs changed slightly in 1204 when King John lost Normandy, but did not really end until after the English were finally expelled from France at the end of the Hundred Years War in 1453.
The result of English disappearing as a written language was the removal of any restraints on language development. This assisted the simplification of the grammar as the folk strove to find the simplest way to communicate with people who did not speak English as their first language.