John intervened in a South Welsh family struggle by backing Rhys Ieuanc and Owain ap Gruffydd against their uncle Rhys Gryg. The younger men had initially opposed the king but changed sides when he offered the force needed to defeat their relative. Their combined Welsh-Norman army won at Llandeilo in 1213 and captured Dinefwr Castle, showing royal power operating through local rivalries rather than English troops alone. The arrangement did not last because the defeat of John's allies at Bouvines shattered his continental position and helped drive England into civil war. With the king unable to focus on Wales, Llywelyn recovered his conquests and secured recognition in the 1218 Treaty of Worcester.
Notable Point · 15:55-17:16
Coalition victory at Llandeilo and reversal after Bouvines
John used a Welsh-Norman family coalition to win at Llandeilo, but defeat abroad and civil war in England let Llywelyn recover.