NOTE: Since writing this piece, I have come across some new information that supports my identification of Caer Dathal with Dinas Dinorwig. Please see
https://mistshadows.blogspot.com/2024/05/caer-dathal-is-actually-identified-in.html
https://mistshadows.blogspot.com/2024/05/caer-dathal-is-actually-identified-in.html
Dinas Dinorwig, Gwynedd, Wales
In December of 2022, I wrote the follwing article:
Why did I decide to move on from the conclusion I had reached regarding Caer Dathal as Dinas Dinorwig? Well, I must admit to "buying into" my clever argument for Dathal as an Irish name whose first component matched that of the Gelert name found at Dinas Emrys (see https://mistshadows.blogspot.com/2021/01/dinas-emrys-as-caer-dathal-late.html) . Plus, the allure of Dinas Emrys, with its folktale of Ambrosius and the two dragons, cast just as powerful a spell over me as it has over many another Arthurian researcher.
Unfortunately, as has so often been the case, precisely because I am not an expert in medieval Welsh, I had relied on some inferior translations of a critical passage in 'Math son of Mathnowy' that accurately pinpoints Dinas Dinorwig as Caer Dathal.
The sentences in question has been perfectly rendered for me by Dr. Simon Rodway only just this morning:
‘Where are the animals you went after?’ said Math. ‘They have made a sty for them in the other cantref below,’ said Gwydion.
Now, the sty is in Arllechwedd at Creuwryon, modern Cororion. Gwydion had brought the pigs to this place from the cantref of Rhos. Cororion's elevation is 95 meters (information courtesy The Historic Place-Names of Wales (https://historicplacenames.rcahmw.gov.uk/). If we travel upstream along the Afon Cegin from Cororion, we come to Dinas Dinorwig in Arfon, the oppidum of the Ordovices, the dominant tribe of Gwynedd in the Roman period. This fort has an elevation of 170 meters. The only other possible site for Caer Dathal would be Caernarfon farther to the SW. But Caernarfon is at a mere 20-30 meters in elevation (with its Twthil - a Middle English word meaning a lookout point - at 60 meters).
issot, the word meaning "below" that is used in 'Math Son of Mathonwy', can be used for 'to the south' as well (according to Dr. Simon Rodway). But Cororion is NE of Dinas Dinorwig, and Caernarfon is even farther to the SW from Cororion than Dinas Dinorwig. In this context, then, issot has to refer to elevation, as in the drop from the summit of Dinas Dinorwig to Cororion. It may also refer to the fact that Cororion is downstream on the Afon Cegin from Dinas Dinorwig.
In other words, the only fort that could be described as having Cororion below it in the neighboring cantref is Dinas Dinorwig.
This identification of Dinas Dinorwig as Caer Dathal fits another passage on the 'Math Son of Mathonwy' story, in which we are told
Thereupon, he [Gwydion] went away angrily, made his way to Caer Dathal, and stayed that night. The next morning he arose, and taking the boy [Lleu] with him, journeyed along the sea-shore between there and Abermenai.
Abermenai was near Caernarfon (see below), itself on the Menai Strait.
If, Dinas Dinorwig is Caer Dathal, then we must allow for Dathal being yet another Irish name, viz. Tuathal.
Professor Hywel Wen Owen had once told me that Melville Richards, the famed Welsh place-name scholar, guessed that Dathal was a Cymracization of the Irish name Tuathal. This has been discussed by other scholars since, including Patrick Sims-Williams in his Irish Influence on Medieval Welsh Literature, p. 172:
Now, I knew that Irish tradition claimed that the famous Tuathal Techtmar (see https://en.wikipedia.org/wiki/T%C3%BAathal_Techtmar) had lived for many years in Britain, and that his mother was the daughter of a British king. It would appear the British king in question resided at the capital of the Ordovices, and was, therefore, the king of that tribe.
We could suppose that what happened was this:
The Roman period oppidum of the Ordovices at some point became the home of Tuathal Techtmar and so took on his name. When exactly this happened it is difficult to say, but that Uther/Cunedda the Irish warlord would have come to reside there need not surprise us. The famous Art son of Conn descended from Tuathal, and the former was the great benefactor of Tadg son of Cian of Cunedda's Ciannachta tribe. Tuathal is said to have founded Mide, which contains the Brega of the Ciannachta.
I will be revising my book THE BEAR KING to reflect this change of identification for Caer Dathal.
What does this mean for Dinas Emrys, though - other than the fact that we can no longer see that fort as being Caer Dathal?
Well, we don't need Dinas Emrys and its dragon story for Uther/Cunedda. Dinas Dinorwig is only a half dozen or so kilometers from Segontium/Caernarfon. The Afon Cegin empties into the Afon Seiont just east of Caernarfon, and the Seiont itself runs just a couple of kilometers south of Dinas Dinorwig. If the Roman period Segontium military unit's shield pattern truly represents two crossed (fighting?) serpents, then surely Dinas Dinorwig is much more likely to have been influenced by this standard than more distant and isolated Dinas Emrys.
Indeed, it is generally believed that Roman Segontium replaced the Ordovician stronghold at Dinas Dinorwig. Hillforts could - and often were - reoccupied after the Roman army withdrew from Britain. So although according to Tacitus the Roman governor Agricola pretty much exterminated the Ordovices, there is no reason why there could not have been sub-Roman or early medieval occupation of Dinas Dinorwig.