Three Unfortunate Counsels of the Island of Britain

To give place for their horse’s fore-feet on the land to Julius Caesar and the men of Rome, in requital for Meinlas (Meinlas is the horse bestowed on Caswallawn in triad 38); and the second: to allow Horse and Hengist and Rhonwen into this Island; and the third: the three-fold dividing by Arthur of his men with Medrawd (Mordred) at Camlann.

Red Book of Hergest | C. 1425
Text of the Mabinogion and Other Welsh Tales | John Rhys, 1887