Cadwgan ap Meurig was a medieval Welsh ruler who reigned over the petty kingdoms

Petty kingdom

A petty kingdom is one of a number of small kingdoms, described as minor or "petty" by contrast to an empire or unified kingdom that either preceded or succeeded it...

 of Gwent and Morgannwg in the tumultuous years of dynastic struggle leading up to the Norman invasion of Wales

Norman invasion of Wales

The Norman invasion of Wales began shortly after the Norman conquest of England under William the Conqueror, who believed England to be his birthright...

.

The chronicler Orderic Vitalis

Orderic Vitalis

Orderic Vitalis was an English chronicler of Norman ancestry who wrote one of the great contemporary chronicles of 11th and 12th century Normandy and Anglo-Norman England. The modern biographer of Henry I of England, C...

 noted in his Historia Ecclesiastica that a Welsh king named "Caducan" suffered defeat in battle at the hands of William FitzOsbern, 1st Earl of Hereford

William Fitzosbern, 1st Earl of Hereford

William FitzOsbern , Lord of Breteuil, in Normandy, was a relative and close counsellor of William the Conqueror and one of the great magnates of early Norman England...

, which would have happened in the year 1070. Subsequently, the Normans established dominance in Gwent and Cadwgan was deposed by an ambitious subject named Caradog ap Gruffydd

Caradog ap Gruffydd

Caradog ap Gruffydd was a Prince of Gwent in south-east Wales who made repeated attempts to gain power over all of southern Wales by seizing the Kingdom of Deheubarth.- Lineage :...

, son of the former king Gruffydd ap Rhydderch

Gruffydd ap Rhydderch

Gruffydd ap Rhydderch was a king of Gwent and part of the kingdom of Morgannwg in south Wales and later king of Deheubarth.Gruffydd was the son of Rhydderch ab Iestyn who had been able to take over the kingdom of Deheubarth from 1023 to 1033...

. Whether killed or merely driven away, the ultimate fate of Cadwgan is unclear.