Moreover, the evidence of both Norse and Irish sources goes to show that all through the ninth and tenth centuries there was extensive intermarriage between the two peoples. Marriages of the invaders with the women whom they had carried off as captives must have taken place from an early period,[58] and we know definitely that the kings and chieftains on both sides frequently strengthened their alliances by unions between members of the royal families. According to the Landnámabók many distinguished Icelanders traced their descent to Kjarval, i.e., Cearbhall, King of Ossory (d. 887), an ally of Olaf and Ivarr. His grandson, Dufthak (Ir. Dubhthach)[59] was the founder of an Icelandic family, and three of his daughters, Kormlöth (Ir. Gormflaith),[60] Frithgerth[61] and Rafarta[62] married Norsemen. The Landnámabók speaks of Kjarval as having been King of Dublin while “Alfred the Great ruled in England… and Harold Fairhair in Norway,”[63] a statement which is often doubted because unsupported by the evidence of the Irish historians; but it is not at all unlikely, since Cearbhall was remotely connected with the Dublin royal house through his granddaughter Thurithr, who married Thorsteinn the Red, son of Olaf the White.[64]
There is no mention of Authr, Olaf’s Norse wife, in the Annals, but we hear incidentally[65] that Olaf, while in Ireland, married a daughter of Aedh Finnliath, King of Aileach. After he became árd-rí (864) Aedh turned against the Norsemen, and having plundered all their fortresses in the north of Ireland marched towards Lough Foyle, where they had assembled to give him battle. Aedh was victorious, and some years after he again defeated the Foreigners, who were at this time in alliance with his nephew Flann; Flann himself and Carlus, son of Olaf the White being numbered among the slain. We also hear of other Irish Kings who were closely related to their Viking opponents. Laxdaela Saga contains an interesting account of a slave-woman who was bought at a market in Norway by an Icelander called Höskuldr. The woman was dumb, but Höskuldr was so struck by her appearance that he willingly paid for her three times the price of an ordinary slave, and took her back with him to Iceland. A few years later, happening to overhear her talking to their little son, Olaf Pái, he discovered to his amazement that her dumbness was feigned. She then confessed that her name was Melkorka (Ir. Mael-Curcaigh) and that she was the daughter of Myr Kjartan, a king in Ireland, whence she had been carried off as a prisoner of war when only fifteen years old.
When Olaf was grown up his mother urged him to visit Ireland in order to establish his relationship with King Myr Kjartan, “for,” she said, “I cannot bear your being called the son of a slave-woman any longer.” Before they parted she gave him a large finger-ring and said: “This my father gave me for a teething-gift, and I know he will recognise it when he sees it.” She also put into his hands a knife and belt and bade him give them to her nurse: “I am sure she will not doubt these tokens.” And still further Melkorka spoke: “I have fitted you out from home as best I know how, and taught you to speak Irish, so that it will make no difference to you where you are brought to shore in Ireland…”[66]
The saga goes on to describe the voyage to Ireland, the landing there, and Olaf’s reception by King Myr Kjartan.
Myr Kjartan may be identified with Muirchertach “of the Leather Cloaks,” King of Aileach, who like his father Niall Glundubh distinguished himself by his spirited resistance to Norse rule in the first half of the tenth century.[67] Donnflaith, another of his daughters and mother of the árd-rí, Maelsechnaill II., married Olaf Cuaran. Their son, Gluniarainn, reigned in Dublin after his father’s retirement to Iona, and appears to have been on friendly terms with Maelsechnaill.[68] The relationship between these two families becomes more complicated owing to the fact that Maelsechnaill’s own wife, Maelmuire (d. 1021), was a daughter of Olaf.[69]
But perhaps no figure stands out so prominently in the Irish and Norse chronicles[70] of the second half of the tenth century as Gormflaith (O.N. Kormlöth) who first married Olaf Cuaran, then his enemy Maelsechnaill II., and finally Brian Borumha, from whom she also separated.
The interchange of family and personal names which took place to such an extent during the Viking period also points to the close connection between the foreigners and the Irish. As early as 835 mention is made of one Gofraidh (O.N. Guthröthr), son of Fergus, who went to Scotland from Ireland in order to strengthen the Dal Riada and died some time after as King of the Hebrides.[71] The Dublin Viking who led an attack on Armagh in 895 had an Irish name, Glun-iarainn, obviously a translation of O.N. Jarn-kné. He was in all probability a relative of Iercne or Jargna (corrupt forms of Jarn-kné) who ruled in conjunction with Zain or Stain (O.N. Steinn) as King of Dublin (c. 850);[72] while other earls of Dublin, Otir mac Eirgni,[73] Eloir mac Ergni or Largni[74] and Gluntradna, son of Glun-Iarainn would also appear to have been of the same royal family.[75] Irish names occur more frequently in Norse families during the tenth and eleventh centuries; we find Uathmaran, son of Earl Bairith (O.N. Barthr); Camman,[76] son of Olaf Godfreyson; Giolla Padraig, Dubhcenn[77] and Donndubhan, sons of King Ivarr of Limerick;[78] Niall, son of Erulb (O.N. Herjulfr); Cuallaidh, son of King Ivarr of Waterford; Eachmarach, and very many others.[79] On the other hand, we may note the prevalence of such common Norse names as Ivarr, Guthröthr, Sumarlithi among the Irish, especially in the eleventh and twelfth centuries. Several of these names still survive, as, for instance, MacAuliffe (O.N. Óláfr); MacCaffrey (O.N. Guthöthr); MacCalmont or Lamont (O.N. Lögmathr); Kettle (O.N. Ketill); Kitterick (? Ir. Mac + N. Sigtryggr); MacKeever (O.N. Ivarr); Manus and MacManus (O.N. Magnus); Quistan (Ir. Mac. + O.N. Eysteinn); Reynolds (O.N. Rögnvaldr); Sigerson (O.N. Sigurthr) and MacSorley (O.N. Sumarlithi).
Both Gaill and Gaedhil, so dissimilar in many ways, benefited by their intercourse with one another. In Ireland the Vikings played an important part in the development of trade; they also promoted the growth of town life. We may trace the beginnings of the seaport towns, Dublin, Limerick, Waterford and Wexford, to the forts built by them near the large harbours in the ninth and tenth centuries. In Dublin coins were minted for the first time in Ireland[80] during the reign of Sihtric Silken Beard (c. 989-1042). Moreover, the large number of loan-words from Old Norse which made their way into Irish shows that the Irish learned in many other ways from the invaders, notably in shipbuilding and navigation.
So far as literature and art are concerned, the period of the Viking occupation is one of the most interesting in the history of Ireland. In spite of the destruction of the monasteries and the departure of numbers of the monks[81] to the Continent the work of the great schools was carried on and there was considerable literary activity;[82] in 914 and 924, respectively, the great crosses at Clonmacnois and Monasterboice were set up; cumhdachs, or book-shrines of plated gold and silver, were made for the three great manuscripts, the Book of Kells, the Book of Durrow and the Book of Armagh; carved gold, silver, and bronze work reached a high level of excellence in the famous Ardagh Chalice and the Tara Brooch; and during the years which intervened between the battles of Gleann Mama and Clontarf, Romanesque architecture was introduced into Ireland. Irish art did not remain wholly free from Scandinavian influence. In the Cross of Cong (A.D. 1123) the Celtic interlaced patterns are found side by side with the “worm-dragon” ornament, while the crosier of Clonmacnois, the psalter of Ricemarsh and the shrine of St. Patrick’s Bell are decorated in the style known as “Hiberno-Danish.”[83]
The Vikings, on the other hand, came under the influences of Irish art and literature. We find marks of Celtic influence not only in the sculptured crosses erected by the Norsemen in the North of England and Man, but even in Scandinavia itself.[84] Moreover, there are strong reasons for supposing that the rise of the prose saga among the Icelanders may be the outcome of their intercourse with the Irish in the ninth and tenth centuries.