MacMurrough granted Fitz-Stephen a share in two cantreds, Bargy and Forth which comprised all the land between Bannow and the town of Wexford. The cantreds were to be held jointly with Maurice FitzGerald, Lord of Lanstephan, his half-brother. The Siege of Wexford lasted only two days. The first attack was repulsed at the loss of 18 Normans and 3 defenders. These are believed to have been the only deaths during the siege. Fitz-Stephen then ordered his men to burn all the ships in the town's harbour. The next morning, the attack on Wexford began again. Shortly after, the defenders sent envoys to Diarmait. The defenders agreed to surrender and renew their allegiance to Diarmait. It is claimed that they were persuaded to surrender by two bishops who were in the town at the time. He was accompanied at the siege by Robert de Barry, the eldest son of his half-sister Angharad de Windsor. Nest then, was the mother of Robert, Maurice and Angharad The Irish launched a counteroffensive in the summer of 1171. Dublin was besieged by a large army under the command of the King of Ireland, Ruadhrí Ua Conchobhair. Fitzstephen sent his best troops to assist the besieged garrison in Dublin, however this left Wexford vulnerable to attack. Lacking the strength to defend the town, Fitzstephen withdrew to Carrick. After taking Wexford he was pursued by the Irish to Carrick where he was besieged. Eventually he was forced to surrender. However, after the Norman garrison in Dublin managed to break the siege, the Irish took Fitzstephen and his men prisoner and retreated, burning Wexford as they withdrew. Taken prisoner by the MacCarthy Reagh in 1171, he was by then surrendered to Henry II of England, who appointed him lieutenant of the Justiciar of Ireland, Hugh de Lacy. Robert rendered good service in the troubles of 1173 and was rewarded in 1177 by receiving from the king of England, jointly with Miles de Cogan, a grant of the kingdom of Cork, "from Lismore to the sea". with the exception of the city of Cork. Cogan was the son of Robert's half-sister Gwladys. The native princes of that province disputed the king's right to dispose of the territory on the grounds that they had not resisted king Henry, or committed any act that would have justified the forfeiture of their lands. In consequence, Fitz-Stephen had difficulty in maintaining his position