Background
Robert"s role in the invasion and colonisation of Ireland, and his position in the medieval Welsh-Irish Norman society, was largely due to his membership of the extended family of descendants of Princess Nest ferch Rhys of Deheubarth. Nest had three sons and a daughter with her husband Gerald de Windsor: the daughter, Angharad, married William de Barry. Nest also had a son - Robert Fitz-Stephen - by her second husband.
William Fitz Odo de Barry was the son of Odo or Otho, a Norman knight who assisted in the Norman Conquest of England and Wales during the 11th century.
William rebuilt Manorbier Castle in stone and the family retained the lordship of Manorbier until the 15th century.
Barry"s brothers were Philip de Barry, Edmond de Barry and Gerald of Wales.
He accompanied his half-uncle Robert to Ireland in 1169 and took part in the Siege of Wexford, where he was wounded. He is mentioned as still engaged in warfare about 1175 by his brother Gerald, the historian, who highly extols his prowess.