Attacked, and with little resistance, slain by Madog ap Rhiryd.

Cadwgan ap Bleddyn (1051-1111) was a prince of Powys in eastern Wales.

Cadwgan was the second son of Bleddyn ap Cynfyn who was king of both Powys and Gwynedd. When Bleddyn was killed in 1075, Powys was divided between his three of his sons, Cadwgan, Iorwerth and Maredudd. Cadwgan is first heard of 1088 when he attacked Deheubarth, forcing its king, Rhys ap Tewdwr, to flee to Ireland. However Rhys returned later the same year with a fleet from Ireland and defeated the men of Powys in a battle in which two of Cadwgan's nephews, Madog and Rhiryd, were killed.

When Rhys ap Tewdwr was killed in 1093, Cadwgan again attacked Deheubarth, but it soon became clear that it was the Normans who would benefit from the death of Rhys. About this time Cadwgan married the daughter of one of the neighbouring Norman lords, Picot de Sai. In 1094 a Welsh revolt against Norman rule broke out, and Cadwgan played a part in this, defeating a Norman force at the battle of Coed Yspwys. Bleddyn was now an ally of Gruffydd ap Cynan, king of Gwynedd, and when Earl Hugh of Chester and Earl Hugh of Shrewsbury launched an invasion in 1098 to try to recover Anglesey for Hugh of Chester, Cadwgan was with Gruffydd. A Danish fleet hired by Gruffydd was offered a higher price by the Normans and changed sides, forcing Cadwgan and Gruffydd to flee to Ireland in a skiff.

They were able to return to Wales the following year, and Cadwgan was able to reclaim part of Powys and Ceredigion, on condition of doing homage to Earl Robert of Shrewsbury. For a while Cadwgan was able to strengthen his position. Earl Robert fell out with the king in 1102 and was defeated with the assistance of Cadwgan's brother Iorwerth. Iorwerth took his other brother Maredudd, captive and handed him over to the king. However many of the lands which Iorwerth had been promised in exchanged for his help were given to Norman lords instead, and Iorwerth broke with the king. In 1103 he was arraigned before a royal tribunal and imprisoned, leaving Cadwgan as sole ruler of the parts of Powys not in Norman hands.

However in 1109 Cadwgan's son, Owain ap Cadwgan, fell in love with Nest, wife of Gerald of Pembroke and launched a daring raid on the castle of Cenarth Bychan to abduct her. Cadwgan tried to persuade his son to return Nest to her husband but failed. The justiciar of Shropshire, Richard de Beaumais promised members of other branches of the ruling house of Powys extensive lands if they would join in an attack on Cadwgan and Owain. Ceredigion was invaded and Owain fled to Ireland, while Cadwgan made his peace with the king but was allowed to hold only one border vill. King Henry I of England later allowed him to have Ceredigion back on condition of paying a fine of £100 and promising to have nothing to do with Owain in future. When his brother Iorwerth was killed by Madog ap Rhiryd in 1111, Cadwgan again briefly took over the rule of all Powys, but later the same year Cadwgan himself was also killed by Madog at Welshpool. Madog was able to seize some of his lands, while the remainder fell to his son Owain.

CADWGAN (d. 1111), prince, was the second son of Bleddyn ap Cynfyn (q.v.). He is first heard of in 1088, when, with his brothers, Madog and Rhiryd, he attacked Deheubarth and drove Rhys ap Tewdwr (q.v.) into exile. Later in the year, Rhys returned with a fleet from Ireland and met the men of Powys in a battle, in which Madog and Rhiryd fell, but from which Cadwgan escaped. The death of Rhys in 1093 seemed to offer an opportunity for renewing the foiled attempt upon the South, but a few weeks sufficed to show that it was the Normans who were to profit, and this on a grand scale, by the untoward event. It was about this time that Cadwgan, as a measure of defence, m. the daughter of his Norman neighbour, Picot de Sai, whom Domesday shows as the lord of Clun and the surrounding area. He took an active part in the Welsh upheaval of the reign of William Rufus, defeating the Normans in 1094 at the battle of Coed Yspwys (its site is unknown) and joining Gruffudd ap Cynan (q.v.) in the defence of Anglesey and the flight to Ireland of 1098. When better conditions enabled the two to return to Wales in 1099, Cadwgan received from earl Robert of Shrewsbury in vassalage his share of Powys and, therewith, Ceredigion. He allowed himself to be drawn into the revolt of the Montgomery family against Henry I in 1102, but escaped the ruin which befell the earl in 1103 and retained his dominions.
The last years of his life were disturbed by the violence and family feuds of the line of Powys. His son Owain (q.v.) was an outstanding offender. The shameless abduction of Nest (fl. 1120) (q.v.) by Owain in 1109 imperilled the position of his father, who was at first left with nothing more than the vill he had received in frank marriage with his wife, but later received Ceredigion. This he lost in 1110, as the result of further misdeeds of Owain; Ceredigion was given to Gilbert Fitz Richard (see under Clare) and became a Norman lordship, while Cadwgan sank into a landless royal pensioner. Again there was a turn of fortune, when his brother Iorwerth was murdered in 1111 by his nephew, Madog ap Rhiryd; the king restored him to southern Powys. But in the same year he also fell a victim to the same unnatural assailant; while planning to build a castle at Trallwng Llywelyn (Welshpool) he was treacherously attacked and, with little resistance, slain.

Cadwgan is described by the ëAnglo-Saxon Chronicleí in 1097 as the ëworthiestí of the Welsh leaders in that year, and his record as a ruler is not discreditable. Besides the two sons, Henry and Gruffydd, born to his Norman wife, he left Owain (d. 1116), Madog, Einion (d. 1123), Morgan (d. 1128), and Maredudd (d. 1124).