a significant era in the history of ireland was the norman invasion of ireland by english or anglo-norman adventurers in 12th century gaelic ireland. in 1166, the once powerful king of leinster, dermot macmurrough (d. 1171), was forced from ireland by his rivals. with the consent of henry, mac murchada sought the aid of henry's vassals in wales and england. through his daughter aoife macmurrough ("fl." 1189), mac murchada gained a matrimonial-alliance with the powerful richard de clare, 2nd earl of pembroke (d. 1176). in 1167, the reinforced mac murchada made his return and easily regained leinster, and later gained further lands. one of the wealthiest and coveted settlements in 12th century ireland was dublin, a seaport and seat of a somewhat independent kingdom ruled by various norse-gaelic kings. in september 1170, the forces of mac murchada and de clare marched on dublin, which was then successfully stormed by de clare's men. according to the near contemporary "expugnatio hibernica" by gerald of wales (d. 1220x23), the leadership of the dubliners managed to escape the carnage with their belongings, and sailed away into the isles.