On the 29 August 1170, following the Norman invasion of Ireland that her father had requested, she married Richard de Clare, 2nd Earl of Pembroke, better known as Strongbow, the leader of the Norman invasion force, in Reginald"s Tower in Waterford.
She had been promised to Strongbow by her father who had visited England to ask for an invasion army. Under Anglo-Norman law, this gave Strongbow succession rights to the Kingdom of Leinster. Under Irish Brehon law, the marriage gave her a life interest only, after which any land would normally revert to male cousins.
But Brehon law also recognised a transfer of "swordland" following a conquest.
