Mediaeval MS image sometimes taken to be a representation of Gruffydd ap Cynan

C18th print from William Stukeley's Itinerarum Curiosum depicting Castell Bryn Gwyn, believed
by some experts to be the site of Gruffydd's grandfather Olaf's castle

Aberlleiniog C12th castle motte, now with C17th stone fortlet

Aber Menai spit, sometimes anciently called South Crook by the English


The Skerries islands, situated in the Celtic Sea some two miles to the north-west of Anglesey, were originally known to the Welsh as the Ynysoedd y Moelrhoniaid, in English the Islands of Seals. In 1075, Prince Gruffydd ap Cynan[1] returned from exile in Dublin to claim Gwynedd as his inheritance on the death of the usurper Bleddyn ap Cynfyn. His claim by descent from Rhodri Mawr, who reigned over Gwynedd from 844-878, was enhanced, in the eyes of his medieval biographer at least, by the fact that his maternal grandfather was Olaf, sometimes written Auloed or Amalach, the Irish-Norse ruler of Dublin. Olaf seems to have had a considerable power base in or near Anglesey in the early 11th century, possibly centred on a stronghold near Moel-y-Don[2] or Llanidan[3].

Gruffydd landed at Aber Menai[4] in Anglesey where, then as now, a projecting gravel and sand spit, formed by long-shore pebble drift, served as the port of the royal court or llys of the commote of Menai at nearby Rhosyr, close to the present-day village of Newborough. From its appearance and location, this landing-place was, after the Edwardian conquest, often referred to in English chronicles as Southcrook. At first, much of Anglesey and Arfon declared for him and he was victorious at the battle of Gwaed Erw, the Bloody Acre[5], successfully storming Rhuddlan castle[6]. However, his forces lapsed into internal strife and he was subsequently defeated at the battle of Bron yr Erw[7] or Erw-yr-Allt in 1075, fleeing via Southcrook to Dublin, taking refuge on the Skerries en route to Ireland. His biographer says

Gwyncu, a baron from Anglesey ... took him against his will from the battle to his ship, which was in Abermenai. And then they went to the island of Adron, namely the island of the seals. Then they voyaged to Wexford in Ireland[8] .

He returned the following year with a new fleet, only to be forced to withdraw once more after losing control of his Irish-Scandinavian mercenaries, who plundered much of Anglesey.

He returned to his land cleaving the deep seas with thirty ships full of Irishmen and men of Denmark; and it was in Abermenai they disembarked[9].

The author relates that the Danes

were angered because they were not getting what they were accustomed to, as had been promised them. And through plunder they took most of Anglesey by force from him, and returned to their land with their ships full of men and riches, and took him also with them, but against his will[10].

After achieving victory over his native Welsh opponents at the battle of Mynydd Carn in 1081[11], his hold on power was further challenged by the first Norman incursions into North Wales around 1090 and at one stage while at Rug, he was taken prisoner by Earl Hugh of Chester. Eventually he contrived to escape to Ireland once more, returning in 1094 to lead a major revolt against the Normans in Gwynedd. He invaded Anglesey with the aid of a Manx fleet of sixty ships but failed to gain a decisive victory, retiring once again to his refuge on the Skerries. The Manx fleet then apparently withdrew, leaving him with only a single vessel.

After the battle was over, the ships sailed to the islands. He [Gruffydd], however, with one ship remained in the island of Ron, namely the island of the seals, plundered a ship coming from Chester, and killed its crew[12] .

Undaunted, he sailed to Nefyn and here raised another force, with which he won back control of Anglesey once again, capturing Aber Lleiniog castle near Penmon. Even this was not the end of Norman aggression. Only with Earl Hugh’s death in battle in Anglesey in 1098 did their incursions cease for many years. Gruffydd went on to reign over Gwynedd until his death in 1137. The name Skerries is Norse in origin ('sharp rocks') and may date from these times. Certainly Gruffydd ap Cynan’s Norse[13] allies would have known the islands by this name.

1. The C12th Historia Gruffud vab Kenan has come down to us in National Library of Wales Peniarth MS 17. The classical edition is Arthur Jones History of Gruffydd vab Cynan Manchester, 1910. A more recent Welsh edition is D. Simon Evans H. G. v. C, Cardiff University Press 1980. An accessible English translation is Evans A Mediaeval Prince of Wales Llanerch Enterprises 1990. Further references are to the latter work.
2. Evans op. cit p.55; the site is named as Bon-y-Dom, plausibly ‘the stump of the motte’; it is generally agreed that this place-name evolved through forms like Bon-y-Don (1504; H. R. Davies The Conway and Menai Ferries, Cardiff 1966 p.65) and Bol-y-Don (C18th; Baron Hill MSS Arch. Camb. 1851) to its present form. If the suggested original meaning is correct, then the present one, viz. ‘bare hill near the waves’ and its C18th form are late and artificial (Sir Ifor Williams showed long ago that in a topographical context, bol is ‘rounded hill’).
3. Both the 1937 Royal Commission Inventory of Anglesey and A. H. A. Hogg Arch. Camb. vol. cxi 1962, consider that Olaf’s fortification may have been at Castell Bryn Gwyn, Llanidan, a late Neolithic or early Bronze age embanked circle re-used in Romano-British times. Leslie Alcock, however, preferred the idea of a coastal site at Moel-y-Don, the remains of which he supposed to have been eroded by the action of the sea.
4. This place is at the extreme western end of the Menai Strait. Aber Menai means literally the mouth or estuary of the Menai and might be applied equally to either the east or west end of the Strait. Nevertheless, there is no doubt of the identification. The Hanes describes Gruffydd returning from Aberlleiniog ‘to the other side of Anglesey where he had three ships’ (Evans op. cit. p.73). At his death Gruffydd bestowed lands, or perhaps income from harbour dues, at Aber Menai upon his wife (ibid. p. 83)
5. R. G. Gruffydd Studia Celtica vol. 15 p.433 doubtfully places the site of Guaet Erw at Dyffryn Glyncul, about a mile north of Aberdyfi around map reference SN6098; Evans op. cit. p.61
6. Evans op. cit. p.62. This cannot of course have been the present edifice, but Rhuddlan was a planted Saxon Borough from the C10th (called Cledamutha) and
there was a motte and bailey fort there (at Twthill) in the C11th.
7. Gruffydd.ibid places the site of Bronn-yr-Eru at SH 434485 near a farm of that name, some 15 miles S.E. of Clynnog.
8. Evans op. cit. p. 63. As for the island of Adron, and a later reference to the island of Ron, note that Middle Welsh *rhon = ‘seal’.
9. ibid p.64
10. ibid p.65
11. Gruffydd op. cit. cites Rev A. W. Wade-Evans as giving a rough map reference SN0136 for Menyd Carn;
12. Evans op. cit. p.72
13. Other Norse place-names so far recognised in Anglesey include Anglesey itself, Priestholm or Puffin Island, the offshore rock Maen Piskar near Rhoscolyn and Osmund’s Air, Gallows Point near Beaumaris; Bedwyr L. Jones and Tomos Roberts Bulletin of the Board of Celtic Studies 1980 p.602