Why Bartrum’s dating of the Demetian Arthur is wrong

To understand why there is a problem with the birthdate of Arthur son of Pedr given by Bartrum, i.e. 560, we need to look at a manuscript that mentions this individual. The names in the tables below are in the same order as they occur in H3859 2, namely progressing from the most recent to later individuals. My allocation of the generation numbers are in the first column and they are based on the principle that the generation number of an offspring should be one greater than that of the parent. The generation number in the fourth column are those given by Bartrum. The first table shows the first segment of the Demetian pedigree. The obits shown in the 3rd column are those stated by Bartrum and originate from the AC.

Gen. H3859 2: 1st seg. Obit acc. Bartrum
Gen. acc. Bartrum Birthdate acc. Bartrum
13 Owain 18 900
12 Elen 929 18
11 Llywarch 904 17
10 Hyfaidd 893 16
9 Tangwystl 15? 790
8 Owain 811 14?
7 Maredudd 796 13
6 Tewdws 12 700
5 Rhain 11 675
4 Cadwgon 11 650
3 Cathen 10 625
2 Gwlyddien 9 600
1 Nowy 9 580
0 Arthur 8 560
-1 Pedr 7 535
-2 Cyngar 6 510

Using my generation numbers, regression analysis of the five obits in the above table give a generation step-size of 28 years. On the basis of this statistical technique and on the assumption that the average life expectancy was 65 years, it follows that an estimate of Arthur’s birthdate is 531, not 560.

Using a much larger database of obits the step-size is 32 years. Indeed Bartrum states a male generation (the period between the birth of a father and that of his child) is about 33 years whereas a female generation (the period between the birth of a mother and that of her child) is about 20 years. The vast majority of generations in my database are male ones.

The larger database gives Arthur’s birth as occuring c. 495, this being the mid-value in the range for gen. 0. The Demetian Arthur’s birthdate is in the period that one would expect for the individual around whom the Arthurian cycle was built.

Using my generation numbering, Bartum’s estimates for the birthdates from Owain to Cyngar in the above table has an average step-size of 26 years, which is far too small. To achieve a more realistic step-size, he has given a number of parents and offsprings the same generation number, viz. Elen/Owain, Cadwgon/Rhain and Nowy/Gwlyddien. This results in a more satisfactory step-size of 33 years, but at the cost of artificially giving parents and offsprings the same generation number.

I believe the reason why Bartrum’s analysis went astray was that he believed H3859 2 to be a single pedigree list, whereas in reality it consists of three seperate segments. In the second segment, shown below, he made use of two dateable events, namely the birth of Gwerthefyr and that of Macsen Wledig. In the Harleian document itself there names take the form Guortepir and Maxim gulecic respectively.

Gen. H3859 2: 2nd seg. Obit acc. Bartrum
Gen. acc. Bartrum Birthdate acc. Bartrum
-1 Gwerthefyr 6 480
-2 Aergol Lawhir 5 460
-3 Tryffin 4 430
-4 Clodri 4? 440?
-5 Clydwyn 3 410
-6 Ednyfed 2 380
-7 Annun (Dyfed) 2 355
-8 Macsen Wledig 388 1 330
-9 Protec
-10 Protector

Gildas writing in the 540s in the DE describes Gwerthefyr, whose name takes the form Vortipor, with the words “… though thy head is now becoming grey … though the end of life is gradually drawing near …”. So, Bartrum’s birthdate for him of 480 cannot be too wrong, although, perhaps, a little on the late side. He errs when he identifies the Macsen Wledig with the Roman emperor Magnus Maximus who died in 388. This forces him to use an average generational step-size for the second segment of 21 years, which is not credible. Again, he circumvents this problem by giving Clodri/Tryffin and Dyfed/Nyfed the same generation number, resulting in a step-size of 30 years.

I believe in this instance the name Macsen Wledig was a reference to the emperor Constantius Chlorus, who died in 306, for the following reasons. He was born in the year 250 and this date falls into the period of my gen -8. His wife was Helena. This tallies with the first part of the Mabinogion tale entitled the Dream of Macsen Wledig  in which  Macsen came to Britain and married Elen Luyddog, the daughter of Eudaf.

It will be noted that there is an anomaly in that Bartrum’s tentative birthdate given to Clodri is 10 years after that of Tryffin who Bartrum believed was his nephew.

The 3rd and last segment of H3859 2 is shown below. Note, the missing names that have been inserted, i.e. Custennin and Macsen Wledig, can be seen in JC20 13.

Gen. H3859 2: 3rd seg.
0 Eifudd
-1 Eiludd
-2 Stater
-3 Pincr misser
-4 [Custennin]
-5 [Macsen Wledig]
-6 Constans
-7 Constantinus magnus
-8 Constantius Elen Luyddog

This segment confirms the identification of Macsen with Constantius, as his wife St. Helena has been given the cognomen of Eudaf’s daughter, namely Luyddog.

Locating Arthur

The Demetian pedigree according to Bartrum.

The Demetian pedigree according to Bartrum.

After fixing Arthur in time to the late 5th/ early 6th century we need to locate him geographically. That so much folklore attached to him suggests it is certain he was regarded as an exceptional leader and if he was the ruler of one of the British kingdoms he is likely to appear in one of the surviving king lists. This narrows the search down to just two individuals: Artur mac Aedan of Dalriada and Arthur map Pedr of Dyfed. However, neither men supposedly lived in the right time frame. According to the AT the former individual died in battle in 596 and, therefore, could not have been also fighting at Badon. Bartrum, the genealogist of the Welsh medieval period, dated the latter ruler to around 560. It would seem this individual too may need to be eliminated from our search. Unless, of course, this dating can be shown to be incorrect, see Why Bartrum’s dating … .