Though birth years of 1208, 1206, and 1215 have been put forward for Dafydd, it has recently been persuasively argued that he was born shortly after Easter 1212[citation needed].

As the diplomatic situation deteriorated, Dafydd began to explore alliances with others against Henry and is known to have sent ambassadors to the court of Louis IX of France.

In August 1245 King Henry again invaded Gwynedd, but his army suffered a defeat in a narrow pass by Dafydd's men.

Dafydd also began diplomacy with Pope Innocent IV, the result of which was a recognition by the Rome of his right to rule over North Wales.

Since Dafydd's marriage to Isabella de Braose, daughter of William de Braose, had failed to produce an heir (though some early modern genealogists record him as having sired sons, including Dafydd[citation needed]) the two elder sons of Gruffydd, Llywelyn ap Gruffudd and Owain Goch ap Gruffydd, divided Gwynedd between them and continued the war with King Henry until April 1247, when Llywelyn and Owain met the King at Woodstock and came to terms with him at the cost of the loss of much territory.

The pair would continue to rule over Gwynedd jointly until Llywelyn's victory over Owain at the Battle of Bryn Derwin in 1255.