the house of ascania was enfeoffed with a reduced duchy of saxony after the fall of henry the lion. the ascanians divided this duchy into the duchies of saxe-lauenberg and saxe-wittenberg. when the male line of the lauenberg branch died out the house of welf which ruled hanover usurped the title, but was later confirmed by the holy roman emperor. after napoleon's defeat the welfs gave saxe-lauenberg to the king of denmark. after the second schleswig war the king of denmark renounced the title, and king william i of prussia, descended from a previous duke of saxe-lauenberg, was elected duke and later annexed saxe-lauenberg to prussia.