Llywelyn ab Iorwerth the Great
d. 1240
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About
Llywelyn ab Iorwerth, Llywelyn the Great, Prince of Gwynedd, mastered all native Wales and held it for forty years, the greatest ruler medieval Wales produced. He married Joan, King John's natural daughter, fought his father-in-law to a standstill, extracted a place for Welsh law in Magna Carta itself, and died in 1240 in the monk's habit at Aberconwy, the abbey he had founded. This line descends from his daughter Gwladus Ddu, Gwladus the Dark, and by a later braid the tree reaches him twice - the second sovereign Welsh ruler in the direct line, and much the greater.
Research notes
✓ LLYWELYN AB IORWERTH 'the GREAT' (1173-11 Apr 1240), Prince of GWYNEDD, effective ruler of all native Wales; m. Joan, natural dau. of King John (their marriage certain; Gwladus's maternity by her disputed, see her record); father of GWLADUS DDU (our line). A DIRECT ANCESTOR - the second sovereign Welsh ruler in the direct line after Gruffydd ap Llywelyn. Source: the standard Gwynedd royal genealogy (Bartrum/Dictionary of Welsh Biography), web-confirmed 6 Aug 2026; these are the documented medieval Welsh king-lists, generally accepted by historians; contested rungs note-only, not hardened.