His second marriage was in in 1205, to Joan, the illegitimate daughter of King John. This was to seal an oath of allegiance to the English Crown, however in 1210 John, nervous of Llewellyn's ambitions, invaded his son-in-law's principality and took control of the territory east of the River Conwy and forcing Llewelyn to the fortress of Snowdonia. Llewellyn was allowed to keep his lands and title of Prince in Snowdonia, but had to accept John as his king, pay the cost of the war as tribute, 20,000 cattle, and relinquish a vast amount of Welsh land.
Later, Llewelyn united the Welsh Princes and regained his land. The English land bordering Wales was controlled by the Normal Lords, appointed by the King. They were known as the Marcher Lords. Llewelyn, in an attempt to gather strength for Wales, married off his daughters to these Lords to consolidate his position. This resulted in peace and stability.
In 1230, Llewelyn hanged William de Braose the Younger, Lord of Brycheiniog, after he had been caught having an alledged affair with Joan.
Llewelyn died in 1240 and was buried in the Abbey of Aberconwy, which he had built in 1189. Subsequently, when Edward I invaded Wales, the Abbey was moved to Maenan and Conwy Castle was constructed where the Abbey had once stood. Llewelyn's sarcophagus was then moved to Maenan. When the Dissolution of the Monastries from 1536, the sarcophagus disappeared. The lower half of the stone casing however remains and can still be viewed in the Wynn chapel of St Crwst's Church in Llanrwst. It is still unknown where Llewelyn's sarcophagus lays.
After Llewelyn's death, Wales once again fell into disunion as Llewelyn's two sons, Dafydd and Gruffudd quarrelled, destroying all that their father had accomplished.
Today, the Welsh are perhaps more well known for their outstanding Welsh lamb (not to be outdone by NZ of course!), great rugby feats and Katherine Zita Jones, but their history remains one of the most fascinating and intriguing as ever.