How did language change as a result of the expansion of Frankish dominion under Charlemagne’s authority?

During the reign of Charlemagne, the Frankish language (which was a Germanic dialect) began to evolve into a new form of language known as Old French. This was due to the expansion of Frankish dominion and the influence of Latin, which was the language of the Church and of educated people across Europe. The Frankish elite, including Charlemagne and his court, were exposed to Latin and began incorporating Latin words and grammar into their language. This process, known as "Langue d'oïl" result in a new dialect of French which is the ancestor of modern French.