Rotrude (or sometimes referred to as Hruodrud/Hruodhaid)[1] (c.775 – 6 June 810) was a Frankish princess, the second daughter of Charlemagne from his marriage to Hildegard.
[2] When she was six, her father betrothed her to the Byzantine emperor Constantine VI, whose mother Irene was ruling as regent.
Either shortly before or after the dissolution of the engagement, King Charles declared that he would never allow any of his daughters to marry - so Rotrude and her sisters Beatrude (sometimes called Beatris or Berta) and Gisella never wed.
The two women authored a letter to Alcuin of York, who was at Tours at the time, requesting that he write a commentary explaining the Gospel of John.
[4] As a result, Alcuin eventually produced his seven-book Commentaria in Iohannem Evangelistam, a more accessible companion to the gospel than St. Augustine's massive and challenging Tractatus in St. John.