A deed of gift issued 1 May 704 in Würzburg by the Thuringian Duke Hedan II to the Anglo-Saxon bishop Willibrord of Utrecht is the first written reference to Arnstadt ("Arnestati"), along with two other towns—the oldest documented reference of settlements in Thuringia and central and eastern Germany. In 726, Arnstadt passed to the Abbey of Echternach, and later to the Abbey of Hersfeld. According to historian August Beck, in 925 the territories of Henry I were extended as a bulwark against the invading Magyars. On 17 December 954, Holy Roman Emperor Otto I made peace in Arnstadt with his rebellious son Liudolf of Swabia and another son, William, whom he appointed Archbishop of Mainz, and decided that the Liebfrauenkirche (Church of our Lady) would be built.