He participated in the Roman War. He joined Lancelot’s defection from Arthur’s court, helping him rescue Guinevere (Guenevere) from the stake and fighting in the battles against Arthur at Joyous Guard and Benoic (Benoye). In return for his support, Lancelot made him the Earl of Angen.
A knight of the same name appears in the non-Arthurian story Sir Cleges.
Alliterative Morte Arthure | c. 1400
Le Morte Darthur | Sir Thomas Malory, 1469-1470