3 Middle English Grammar: general overview
Early Middle English (1100-1300) has a largely Anglo-Saxon vocabulary (with many Norse borrowings ill the northern parts of the country), but a greatly simplified inflectional system. The grammatical relations that were expressed in Old English by the dative and locative cases are replaced in Early Middle English with prepositional constructions. This replacement is, however, incomplete: the Old English genitive n-es" survives in the modern Saxon genitive—it is now called the "possessive*1: e.g., the form "dog's" for the longer "of the dog". But most of the other case endings disappeared in the Early Modern English period. The dual grammatical number (expressing exactly two of a thing) also disappeared from English during the Early Modern English period (apart from personal pronouns), further simplifying the language.
Deeper changes occurred in the grammar. Gradually, the wealthy and the government anglicised again, although Norman (and subsequently French) remained the dominant language of literature and law for a few centuries, even after the loss of the majority of the continental possessions of the English monarchy. The new English language did not sound the same as the old; for, as well as undergoing changes in vocabulary, the complex system of inflected endings Old English had, was gradually lost or simplified in the dialects of spoken Middle English. This change was gradually reflected in its increasingly diverse written forms as well. The loss of case endings was part of a general trend from inflections to fixed word
order that also occurred in other Germanic languages, and therefore cannot be attributed simply to the influence of French-speaking sections of the population: English did, after all, remain the language of the vast majority. It is also argued that Norse immigrants to England had a great impact on the loss of inflectional endings owing to their semi-mutually comprehensible (to the native English speakers) vocabulary, but lack of capability to reproduce their endings; or that the morphological simplifications were caused by bilingual Romano-Britons in Old English and Brittonic (which lacks noun case) or British Romance (which may have lacked noun case, too, like most modern Romance languages do).
With its simplified case-ending system, the grammar of Middle English is much closer to that of modern English than that of Old English.
The English language changed enormously during the Middle English period, both in grammar and in vocabulary. While Old English is a heavily inflected language (synthetic), an overall diminishing of grammatical endings occurred in Middle English (analytic). Grammar distinctions were lost as many noun and adjective endings were leveled to -e. The older plural noun marker -en largely gave way to -s, and grammatical gender was discarded. Approximately 10,000 French (and Norman) loan words entered Middle English, particularly terms associated with government, church, law, the military, fashion, and food.