The Nuttall Encyclopedia
An entrenchment and rampart between England and Wales, 100 m. long, extending from Flintshire as far as the mouth of the Wye; said to have been thrown up by Offa, king of Mercia, about the year 780, to confine the marauding Welsh within their own territory.
Wood, James, ed. Entry for 'Offa's Dyke'. The Nuttall Encyclopedia. https://www.studylight.org/encyclopedias/eng/nut/o/offas-dyke.html. Frederick Warne & Co Ltd. London. 1900.