In 842, The Strasbourg Oath of Allegiance written in Old German and Old French, decided the way Europe would be divided up under Charlemagne.In the 11thC, the Ottonian emperors founded the German Holy Roman Empire with Alsace playing an important role.
From 1048 to 1054, Leo IX, a pope originally from Alsace, modernised the Church.In the 12thC, the Hohenstaufens established their imperial power-base in Alsace, founding a number of towns there; Hagenau became one of their capitals.