Gruffydd ap Llywelyn or Llewelyn (grĭfˈĭħ äp hləwĕlˈĭn, lōĕlˈĭn) [key], d. 1063, ruler of Wales (1039–63). A series of campaigns against other Welsh princes made him the ruler of virtually all Wales. Allied with the outlawed Ælfgar of Mercia, he launched a series of raids into W England, but his power was broken by Harold in two invasions (1062–63). His defeat plunged Wales into confusion and paved the way for the conquest of Wales by the Normans. His name also appears as Griffith ap Llewelyn.
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