This article recalls the history of the territories that make up today's Belgium and the Netherlands, marked by a break in the continuum of Germanic languages in this region. In the Middle Ages, Flanders was the most dynamic area, but the 16th century saw a shift: the Wars of Religion led to a revolt against the Habsburg domination, which resulted in the reconquest of Flanders and the independence of the northern provinces. From then on, separate memories developed, reinforcing local sociolinguistic differences. While the Netherlands became an autonomous society with its own language, in Flanders the educated strata of society adopted French, leaving Flemish to the working classes. The result has been a continuing tension between Flemish and Dutch in defining the most legitimate form of the language.