 Though gradual, English experienced a dramatic change from Old English, a moderately inflected language using a complex case system, to Modern English, considered a weakly inflected language or even analytic.Important deflexion changes first arrived in the English language with the North Sea Germanic (Ingvaeonic) shifts, shared by Frisian and Low German dialects, such as merging accusative and dative cases into an objective case.Viking invasions and the subsequent Norman conquest accelerated the process.