When the Norsemen first saw the approaching fleet they were much alarmed. Some said it was reinforcements from Norway, but others, with keener insight, said they were Danes who were coming to harry and plunder. A swift vessel was dispatched to find out who they were, and when the steersman called out to them inquiring from what land they came and whether as friend or foe, the only answer was a shower of arrows. A fierce battle ensued, in which the Danes killed thrice their own number and carried off the women-folk and property of the Norsemen. In 851 they plundered the Norse settlements at Dublin and Dundalk, but in the next year the Norsemen attacked them in Carlingford Lough. At first the Danes were defeated, but then their leader cunningly exhorted his men to secure by their prayers and alms the patronage of St Patrick, who was incensed against the Norsemen because of the many evil deeds they had wrought in Erin. The battle was renewed and the Danes were victorious. After the battle they made rich gifts to St Patrick for 'the Danes were a people with a kind of piety: they could for a time refrain from meat and from women.' After the fight we learn that the Danes cooked their meat in cauldrons supported on the bodies of their dead foes. The Danes now helped Cerbhal, king of Ossory, against the Norsemen who were harrying Munster, and henceforward we hear again and again how the various Irish factions made use of the dissensions among the invaders to further their own ends. Matters were further complicated by the fact that many of the Irish forsook their Christian baptism and joined the Norsemen in their plundering. These recreant Irish were known as the Gaill-Gaedhil (i.e. the foreign Irish), and played an important part in the wars of the next few years. The Gaill-Gaedhil were undoubtedly a race of mixed Norse and Gaelic stock and we must not imagine that they sprung suddenly into existence at this time. Long before this the Norsemen and the Gaels must have had considerable peaceful intercourse with one another in their various settlements, and in accordance with well-established Scandinavian custom it would seem that many of the Irish were brought up as foster-children in Norse households and must soon have learned to accept their religion and customs. There was also extensive intermarriage between Norsemen and Irish. The annals speak of several such unions, the most famous being the marriage of Gormflaith, afterwards wife of Brian Borumha, to Anlaf Sihtricsson, while in the genealogies of the Norse settlers in Iceland at the end of this century, Gaelic names are of frequent occurrence. One of the most famous of the leaders of these 'foreign Irish' was Ketill Finn (i.e. the White), a Norseman with an Irish nickname. These foreign Irish fought either by the side of the foreigners or on their own account and we have an interesting story telling how, when Vikings from Ireland made an invasion of Cheshire (c. 912), Aethelflæd, the lady of the