What year did Otto I, Holy Roman Emperor's mother become Duchess of Saxony?
Otto I, Holy Roman Emperor:  He was the oldest son of Henry I the Fowler and Matilda. Matilda of Ringelheim: Saint Matilda (  894/97 – 14 March 968) was Duchess of Saxony from 912 and German queen (Queen of the Franks) from 919 by her marriage with Henry the Fowler, the first king of the Ottonian dynasty.
912