In the wars of Arthur, as recounted by Geoffrey of Monmouth (Gruffydd ab Arthur), Kadwr or Cador bore a conspicuous part. He shared the dangers of the expedition against the Romans, and was present at the battle in which the emperor of Rome was slain. He assisted at the coronation of Arthur at Caerlleon upon Usk. Kadwr is mentioned in the Triads as one of the three battle knights, who fled neither for spear, nor arrow, nor sword, and who never shamed their leader in the day of conflict.
His son Cystennin (Constantine ab Cador) succeeded Arthur in his kingdom. Tegau Eurvron, the virtuous wife of Caradawc Vreichvras, and the heroine of the Mantel mal taille', appears to have been the sister of Kadwr.
Taliesin alludes to him in his poem entitled the Glaswawd-
"He will spare no kindred,
Neither cousin nor brother;
At the sound of Kadwr's horn
Nine hundred are stunned."
Myv. Arch. I. p. 64.
