He put up a good fight, but on December 11, 1282, Llywelyn the Last, the last native-born Prince of Wales, died in battle, clearing the way for King Edward I to take over Wales completely (and name his own heir as its new prince).
Llywelyn started doing battle against the English when he was only in his early 20’s—supporting his uncle, Dafydd, against King Henry III. When Dafydd died in 1246, Llywelyn took the throne and came to terms with Henry the following year, signing the Treaty of Woodstock. The treaty restricted Llywelyn to the part of Gynedd west of the River Conway; the area east of the river became Henry’s.
Eventually, however. Llywelyn wanted more, and aided by a younger brother, he set out to take it, defeating an English army at the Battle of Cadfan in 1257. After another decade of fighting, he was recognized as Prince of Wales by King Henry.
Despite being officially recognized, things didn’t get easier for Llywelyn. His younger brother turned against him and, after a failed assassination attempt on Llywelyn, fled to England, where he was protected by the new king, Edward I. Edward declared Llywellyn a rebel in 1276 and gathered an enormous army to march against him. After capturing the harvest, Edward forced Llywellyn to come to terms with him, and an agreement was reached whereby Llywellyn once again lost almost all his lands. Things remained peaceful for a little while, but then many of the Welsh princes who’d gone over to the English side—including Llywellyn’s younger brother Dafydd—decided they weren’t happy with Edward, and they started a revolt that Llywellyn reluctantly joined. Llywellyn was killed during the Battle of Orewin Bridge. Dafydd kept fighting for a few more months, but Welsh morale was destroyed, and after Dafydd’s capture and execution the following year, Edward was free to take over Wales. The grandson of Llywellyn’s youngest brother claimed the title Prince of Wales some years after his great-uncle’s death, but after his assassination in 1378, the male bloodline of the family is believed to have become extinct.