Redcastle and Whitecastle

Authentication of the Genealogy

The MacLochlainn genealogy subsequent to 1241 survives as a text within the O Clery Book of Genealogies [1] a genealogical collection compiled by Cuchoigriche O Clery whose death occurred sometime after 1664 [2]. The text is in a single hand with no subsequent additions [3]. No earlier editions of the MacLochlainn genealogy are known to have survived. Several later editions exist but all appear to be simple copies of O Clery. The following chart encompasses the full extent of the genealogy as given by O Clery but contains only those lines which can be dated at some point along their length. Note that the text is presented in columnar format and that elsewhere I have sought to preserve the threefold division indicated in the pattern of its column breaks by giving the text in the form of three separate charts headed by the individuals highlighted. Note that Aibhne and Fhoibhne arise as alternate spellings of the name of a single individual and that An Oifistel is an individual whose personal name has not survived but who is instead given as holding the office of an oifistel ('the official'). Dates shown in normal text are the result of cross referencing individuals to dated events in other source records and are discussed elsewhere. Undated individuals are indicated by numbers representing their generational distance from Domhnall of Cameirge. Dates shown in italics are estimated based upon dead reckoning at the standard thirty three years per generation from a dated individual (died to died, alive to alive, killed to alive). Names have been standardised.

Domhnall of Cameirge killed 1241
 |                   |
 1                   1
 |                   |
Diarmaid killed 1260 2
 |                   |
 3                   3
 |                   |
Sean died 1375       4
 |                   |
 5                   5
 |                   |_______________________________________________________
 |                   |                                                       |
 6                  Aibhne/Fhoibhne alive 1440                              unknown/An Oifistel alive 1440
 |                   |____________________________________                   |
 |                   |                                    |                  |
 7 died 1474         7                                    7                  7
                     |                                    |                  |
                     8                                    8                  8
                     |_______________                     |                  |
                     |               |                    |                  |
                     9               9                    9                  9
                     |               |________________    |                  |
                     |               |                |   |                  |
                    Sean alive 1621 Aedh alive 1621   10 Domhnall alive 1621 10
                                    Eoghan alive 1621 |                      |
                                                      11                     11
                                                      |                      |_________________
                                                      |                      |                 |
                                                      12 alive 1687         Donncha alive 1606 12
                                                                             |                 |
                                                                             13 alive 1639    Eoghan alive 1621
                                                                                              Conor alive 1606

With the exception of a short narrative identifying two brothers of Domhnall of Cameirge (which I have dealt with elsewhere) the genealogy is formed entirely of ascents, most of which commence with several brothers rather than an individual on their terminal (ie: most recent) generation. We should therefore expect the appearance of the genealogy when recast as a chart to be composed of somewhat sparse vertical stems in contrast to the dense horizontal networks that would arise if it were a collection of descents. What we do find is that while the charts given elsewhere for Domhnall of Cameirge and An Oifistel are indeed somewhat sparse the chart for Aibhne is so dense that I have had to present it in a semi-vertical format in order to allow it to display fully on the screen. The Aibhne branch would thus appear to be the most fully recorded within the genealogy, which is perhaps not surprising as all of the known chiefs of the clan in the seventeenth century were descendants of Aibhne.

To proceed with the authentication, an examination of the dating of the terminal generations uncovers a stratum marked by a line prematurely terminating circa 1474. This indicates that a compilation of oral genealogies into written form occurred approximately two hundred years after 1241, encompassing at its extreme a person who died circa 1474. It also indicates that O Clery used this now lost compilation as the basis of his own, copying and merging it with oral genealogies covering the two hundred year period from the first compilation up to his own time, encompassing at its extreme a person alive circa 1687. Oral genealogies of two hundred years can be presumed to have been recalled fairly accurately within the kin-based society existing at that time and so with the earlier portions gaining assurance from the convergence of collateral ascents this embedded stratum gives us confidence that the genealogy is reasonably accurate and contemporaneous throughout its full length.

The chronology of the prematurely terminating branch presents no problems. The average generation length between Domhnall killed 1241 and Diarmaid killed 1260 is only ten years but this is not unusual considering that they were grandfather and grandson who died violently. In any event the line resolves into the standard average generation length of thirty three years between Domhnall killed 1241 and Sean died 1375. When considering the rest of the chronology it becomes apparent that the number of generations between Aibhne and An Oifistel circa 1440 and the terminal generations of the seventeenth century imply a twenty eight year average generation length within the branch descending from An Oifistel but a very different forty five year average generation length within the branch descending from Aibhne. Given the existence of one five generation line and one six generation line diverging early on within the An Oifistel branch, it seems likely that the longer seven and eight generation lines which form the main body of this branch are the result of a couple of generations of around twenty years soon after the divergence of the shorter from the longer lines. This would account for the short average generation length found within the An Oifistel branch. The long average generation length found within the Aibhne branch can be resolved if we give the line from Domhnall of Cameirge to Aibhne a generation length longer than the thirty three years previously assumed. If for instance we assume that Aibhne was alive at (say) circa 1470 this would imply a not unreasonable generation length of thirty eight years between both Domhnall of Cameirge and Aibhne and between Aibhne and the terminal generations [4]. As Aibhne and An Oifistel are given as brothers by O Clery [5] this would work to upset the chronology previously established within the An Oifistel branch, though not unreasonably so. In comparing these branches, the Aibhne branch as the most fully recorded within the genealogy has the greatest structural integrity in terms of mutual assurance from collateral ascents and so is inherently more suited to act as control on the An Oifistel branch than vice versa. The difference in generation lengths would thus appear to indicate a structural problem within the An Oifistel branch if anywhere, but the lack of any obvious interpolation causing lines to lengthen within that branch (eg: a duplicated string of names) taken together with the direction of enquiry (we are looking for something that is present rather than something that is absent) gives us considerable comfort that there is in fact no such problem.

The alternative to this equilibrium approach is to find that there is a structural problem at the point at which the Aibhne and An Oifistel branches diverge, to break the genealogy apart and posit that An Oifistel was perhaps uncle or great-uncle to Aibhne rather than his brother thus explaining the longer lines found in the An Oifistel branch. The stratum embedded around the time of this divergence, however, points against such a finding as it indicates that the relationship of Aibhne to An Oifistel was contemporary within the personal knowledge of those who provided the oral genealogy captured at the time of the first compilation. While it remains a possibility that the genealogies of Aibhne and An Oifistel were simply not captured within the first compilation so that the lines of their descendants are unstratified all the way back to Domhnall of Cameirge so raising doubts as to reliability in their earlier range, Aibhne and An Oifistel as brothers descending from a stem-like line of only sons present every appearance of being an embedded terminal generation and so their relative position within the genealogy would seem to have the force of contemporary knowledge. Furthermore, that different strata have in the past been joined at this point is indicated within the text by its most blatant anomaly, the double counting of Aibhne and Fhoibhne as alternate spellings of the same name and the overwriting of a personal name now lost by the designation An Oifistel. We can with some confidence therefore conclude that the MacLochlainn genealogy was first compiled in the fifteenth century, that this compilation survived until the seventeenth century in an edition that has now been lost, that this edition was used as the basis for a second compilation by O Clery in the seventeenth century that has survived and that this genealogy has every appearance of being authentic.



  1. The O Clery Book of Genealogies, S. Pender, Analecta Hibernica 18, paragraphs 308-335.
  2. ibid, xv - xviii.
  3. Royal Irish Academy 23 D 17, 33 and 34.
  4. Date guessing and pedigrees, M. Miller, Studia Celtica 10/11 calculates the average generation length within the well authenticated early medieval Irish royal lines of Aileach, Meath and Brega at 36 years. The origins and ancestry of Somerled, W.D.H. Sellar, Scottish Historical Review 45 shows the average generation length within the late medieval lines of O Donnell, O Neill and MacDonald to be 41, 37 and 41/42 years respectively.
  5. The ancestry of Aibhne in paragraph 312 is identical to that of An Oifistel in paragraph 327.