Catholic Encyclopedia (1913)/St. Alfrida
Alfrida, Saint, virgin, and recluse, c. 795. This saint, whose name is variously written Elfthritha, Ælfleda, Æfthryth, Alfritha, Etheldreda, etc., was a daughter of King Offa of Mercia. According to a late and not very trustworthy legend she was betrothed to St. Ethelbert, King of the East Angles, but when he came to the court of Offa to claim her, he was treacherously murdered by the contrivance of Cynethritha, Offa's queen. After this Alfrida retired to the marshes of Crowland, where she was built into a cell and lived as a recluse to the end of her days. It is impossible not to suspect the existence of some confusion with Ælfleda, another daughter of Offa, whose husband was also murdered by treachery.
Acta SS., 2 August; Stubbs in Dict. Christ. Biog., II, 82, s.v. Elfthritha; ibid., 215 s.v. Ethelbert; Dunbar, Dict. of Sainted Women, I, 44; Stanton, Menology, 221. For Brompton's account see the Bollandists and the works of Giraldus Cambrensis, III, 411–420.