Henry's interference in Ireland sprang from more complicated causes. Ireland in the twelfth century was--as it had been since the first dawn of history--a group of Celtic principalities, always engaged in weary tribal wars with each other. Sometimes one king gained a momentary superiority over the rest, but his power ceased with his life. In the ninth century the island had been overrun by the Danes; they had not succeeded in occupying a broad _Danelagh_ such as they won in England, but had built up a number of small kingdoms on the coast, round their fortified strongholds of Dublin, Wexford, Waterford, and Limerick. These principalities still existed in Henry's time, while the interior was held by the five kings of Ulster, Munster, Connaught, Meath, and Leinster. At this moment Roderic O'Connor of Connaught claimed and occasionally exercised authority as suzerain over the other kings. But he had no real power over the land, which lay half desolate, had become altogether barbarous, and teemed with cruel and squalid tribal wars. The introduction of this distressful country into English politics may be laid at the door of Dermot McMorrough, King of Leinster. This prince had been driven out of his realm by his suzerain, Roderic, King of Connaught, because he had carried off the wife of Roderic's vassal, O'Rourke, Lord of Breffny. Dermot came to England, and asked aid of Henry II., who, as we have already seen, had long possessed a papal Bull, authorizing the conquest of Ireland.[15] Henry would not stir himself, being in the midst of troubles with the King of France, but gave the exiled king leave to obtain what help he could from the English barons. Dermot placed himself in the hands of Richard de Clare, nicknamed Strongbow, Earl of Pembroke, a warlike but impecunious peer who had great influence in South Wales. Richard raised a small army of Anglo-Norman knights and Welsh archers--less than 2000 men in all--and landed in Ireland to restore Dermot to his throne. He met with quite unexpected success, sweeping Dermot's enemies out of Leinster, and conquering the Danish princes of Wexford and Dublin. He married Dermot's heiress Eva, and on the king's death in 1171 succeeded him as ruler in his kingdom. Other barons and knights from South Wales came over to join him, and they obtained a complete mastery over the native Irish, whose light-armed bands could not resist the charge of the mail-clad knights or stand before the archers, even when they were in overwhelming numerical superiority. In a battle before the gates of Dublin, a few hundred followers of Strongbow routed the whole host of Roderic of Connaught, though he was supported by a considerable body of Danish Vikings. [Sidenote: =Henry invades Ireland in person.=]