Owain Gwynedd ap Gruffydd was King of Gwynedd, a principality in north-west Wales. He is, however, known as "Owain the Great" for his claim to be King of all of Wales. His father, Gruffydd, had reigned for 62 years and increased the power of the Gwynedd from his power base on Anglesey. Until the accession of Henry II of England in 1154, Owain achieved great military successes, pushing his borders further east into the kingdom of Powys. However, Henry II invaded in 1157, and eventually Owain was forced to give up his conquests in the east.
Editors. "Owain the Great of Wales". The Literary Encyclopedia. First published 31 July 2012
[http://www.litencyc.com/php/stopics.php?rec=true&UID=804, accessed 25 April 2017.]