Chronological Synchronisation of the Irish Annals

D.P. Mc Carthy

Department of Computer Science, Trinity College, Dublin 2.

Edition History



1 Mar. '99

First edition to accompany publication of PRIA 98C(1998)203-55. Collation covered the years AD 306-722

1 Sep. '99

Second edition - Collation extended backwards to cover the years AD 1-722 and to include Bede's Chronicon Maiora. The tables have been divided into c. 70K byte units to facilitate Web downloading and on-going maintenance.

19 Sep. ‘00

Third edition – Full collation extended forward to cover the years AD 1-766 and partial collation of AT, CS, AC and AU continued from thence to AD 1178


The purpose of this document is to describe the principles used in the construction of the tables which synchronise the major annalistic collections by collating tokens of their chronological (e.g. Kl.ui.) and record entries (e.g. Patricius pervenit ad Hiberniam …) in parallel. This process has been described in detail in pp. 215-21 of my paper ‘The Chronology of the Irish Annals’ published in the Proceedings of the Royal Irish Academy 98C(1998) 203-255, to which this document serves as an appendix. The primary aim of this collation is to establish a single chronological structure, based on a critical examination of all the MSS chronological and record criteria, into which all the annalistic records may be placed. In this way a uniform, synchronized chronology will be established for all the Irish annals. A secondary aim of the collation is to provide a clear view of the relative content of all the major annalistic collections, i.e. to identify as far as possible their common and their unique entries, in order to gain insight into their common and individual text histories.

Because the character of the annals changes over time, for example ferial data is found continuously only in the annals of Tigernach (AT) and the Chronicon Scotorum (CS) only up to AD 655, and because all the collections present lacunae, the principles of collation must also change over time. I give here below an outline summary of the principles relevant to each major interval of collation:




The ferial data of AT/CS, together with full collation of all the annals allows reconstruction of the chronology of their common source, the Iona Chronicle. However it emerges that thirteen kalends have been lost and these must be carefully restored and this process is described in detail below.


The chronology of this interval may be established from the parallel collation of the kalends of AT/CS/AU. Because this interval covers the relocation of the Iona Chronicle to Ireland in c. AD 740 it is important to identify the common and unique content of each of the collections, thus nearly all their records have been fully collated.


The chronology of this interval may be established by parallel collation of the kalends of AT/CS/AU, wherever these are available, together with their ferial, epactal, Paschal cyclic, bissextile and ab Anno Incarnatione data. However the typically large number of record entries per annum over these years renders full collation of all the record entries infeasible, and instead, as far as possible a minimum of one common event per annum between each pair of annals is used to confirm their synchronism. However in order to exhibit the content relationship between the annals a full collation at intervals and at known critical stages has been undertaken.

Finally because it is frequently found that annals record entries vary from one to another in both their semantic and their textual details the following cryptic notation has been employed to represent these differences:


Semantic relationships - n.b. if no textual relationship is expressed, is assumed




Semantic content of X and Y is identical.

X» Y

Semantic content of X and Y is nearly identical.

X¹ Y

Semantic content of X and Y differs significantly.


Semantic content of X is greater than that of Y.


Semantic content of X is less than that of Y.

X »Y

Semantic content of X is much greater than that of Y.

X «Y

Semantic content of X is much less than that of Y.

Textual relationships, which refer to the word, not orthographic, level


Text of X and Y are verbatim, and hence Þ X=Y.

Text of X is related to that of Y.


Text of X is unrelated to that Y.


X» Y, X.tu.Y

X and Y say the same thing in different words.


X says more than Y, and there is a textual dependency.


X and Y are verbatim and hence X=Y.

X « Y,

X equals a small part of Y and is textually related.

X=Y» Z

Z differs slightly from X and Y, which are close and are related.


Z has less than X or Y, and are all related


X, Y and Z all say the same thing and are all related


X says more than Y says more than Z, and are all related.

Restoration of the Chronological Integrity of AT/CS over AD 1-664

In the paper, ‘The Chronology of the Irish Annals’, I established that the ferial data preserved in the annals of Tigernach (AT) and the Chronicon Scottorum (CS) represent the oldest stratum of chronological apparatus in the Irish annals; note that all page, section, figure and appendix references in this article are to this paper, unless otherwise stated. These ferial data thereby offer us the most plausible basis on which to recover the original chronology of the early medieval annals. The earliest known example of this chronological apparatus occurs in the Paschal tract De ratione paschali of Anatolius of Laodicea, which was cited by Rufinus in the early fifth century in his edition of Eusebius’ Ecclesiastical History, and it appears that Rufinus subsequently employed it in the composition of a chronicle, as is discussed in D.P. Mc Carthy ‘The Status of the pre-Patrician Irish Annals’, Peritia 12 (1998)98-152. The same apparatus was employed shortly afterwards by Sulpicius Severus in his composition of his Paschal table, the latercus, and then subsequently in the sixth century S. Columba extended Rufinus’ Chronicle, and this extension was continued by his successor abbots at Iona at least up until the middle of the seventh century. The ferial data in AT/CS are found to commence at the Incarnation and to continue, with occasional errors in the placing of bissextile years, up until AD 424 where a sudden disruption to the ferial sequence occurs, followed by another 208 years of cogent ferial data; this entire sequence is tabulated in Appendix 1, and see the section The ferial sequence of AT/CS from the Incarnation to the seventh century, pp.221-3, for the relevant discussion. When the chronological accuracy of this ferial structure was examined for those events with independently-known AD dates it was shown in The chronological accuracy of AT/CS, pp. 223-9, that:


Seven kalends had been removed at AD 425-431.


Five kalends had been removed between AD 612-635.


One kalend had been removed between AD 635-664.


The ferial data between AD 1-63 and AD 397-424 inclusive are properly synchronised with the Julian calendar.


From AD 425 onward every fourth ferial datum had been decremented by one, excepting for the seventeen inclusive years from AD 524-540, which are correctly synchronised to the Julian calendar.

The purpose of this section is to use this information to restore the chronological integrity of both AT and CS, and thus to provide a uniform chronological structure for the collation of all the other annal collections.

Up until AD 424 there is no difficulty about this and we simply use the Annus Kalendae defined from the sequence of kalends tabulated in Appendix 1 from 1.1 to 16.4 inclusive, see the section The ferial sequence of AT/CS from the Incarnation to the seventh century, pp.221-3. These data are mostly derived from AT, but from 12.28 to 13.22 they are taken jointly from AT and CS, and from 13.23 to 16.4 from CS alone. Immediately following AD 424 we must restore the first seven kalends for the years AD 425-431 which is then to be followed by the sequence of kalends in Appendix 1 from 16.5 to 22.17. In this way all of the events from AD 432-612 are restored to their appropriate AD years, cf. Table 5, p. 225. Next, regarding the five kalends which have been removed from the twenty four years AD 612-635, we immediately encounter the difficulty that we have no means of discovering from exactly where in this interval the kalends were removed. In this circumstance the best we can do is to distribute the restored kalends uniformly over the whole interval and, since 24÷5 » 5, they should be placed at intervals of five years commencing one half-interval after AD 612. Hence we restore the eighth kalend at AD 614 and the remaining four at AD 619, 624, 629 and 634 respectively. Finally, for the remaining kalend which was removed somewhere between AD 655-664, since again we do not know precisely from whence it was omitted, the median postion at AD 659 is the best we can do. To summarise these restorations:


Restored kalends nos. 1-7 placed at AD 425-431.


Restored kalends nos. 8-12 placed at AD 614, 619, 624, 629, 634.


Restored kalend no. 13 placed at AD 659.

With these thirteen restorations we find that all the events in the interval AD 612-664 for which we have independent AD dates are restored either precisely or very closely to these dates, as may be seen from the following table:










Isidore’s Chronica Maiora




Volcano of AD 627



Mc Carthy & Breen

Baptism of Edwin



Bede HE v.24

Lindisfarne founded




Heracleonas reigned



Enc. Brittannica

Death of Fursey




Death of Aidan



Bede HE v.24

Death of Penda



Bede HE v.24

Death of Cumine Fota



Walsh & Ó Cróinín

Eclipse of 1 May 664



Mc Carthy & Breen

As may be seen all these events are placed under the synchronised AD to within one year of their independently known AD dates. It should be noted that restoration of these six kalends has absolutely no effect on the sequence of the annals' record of events, and furthermore, the close correspondence between the synchronised and independent AD suggests that, over these years, both the intervals between these events and the synchronised AD data are accurate to within about two years. After AD 664, as discussed in Chronology of the other annals compared with AT/CS at p. 231, the evidence shows that AT/CS and AU preserve identical chronologies from AD 664 at least up until AD 722. The authorities cited above for the independent AD data are:

F.L. Cross & E.A. Livingstone (Edd.), The Oxford Dictionary of the Christian Church (Oxford 1983).

D.P. Mc Carthy & A. Breen ‘An Evaluation of Astronomical Observations in the Irish Annals’, Vistas in Astronomy, vol 41, no. 1 (1997)117-138.

Bede’s Historia Ecclesiastica edited and translated by B. Colgrave and R.A.B. Mynors as Bede’s Ecclesiastical History of the English people (London 1991).

Encyclopaedia Brittannica 19(1970) 529-39.

D.H. Farmer The Oxford Dictionary of Saints (Oxford 1978).

M. Walsh & D. Ó Cróinín Cummian's Letter De controversia paschali and the De ratione conputandi, Pont. Inst. of Med. Studies (Toronto 1988)


I now discuss in turn the considerations arising in the collation of each of the annals; see also the section Chronology of the other annals compared with AT/CS, pp. 229-39 for other relevant details.

Annals of Tigernach and Chronicon Scotorum

Since these are the primary witnesses to the chronology up to AD 664 both their chronological and record tokens have been fully tabulated in the order in which they occur in each MS and, as far as possible, these tokens have been aligned by placing tokens of corresponding events on the same line of the collation. Very occasionally, because one source has re-sequenced the event, they cannot be aligned and in these cases an opinion is expressed in the ‘Remarks’ column, based on the order of the records in other sources and sometimes textual details, as to which source has re-sequenced the record. As will be seen the re-sequencing is most frequent in CS where it appears to be the result of subsequent restoration of records omitted from the initial compilation. Where it has been found that either of these sources has either omitted or interpolated a kalend, then these have been restored in the conventional manner, i.e. either [Kl.] or (Kl.). Following AD 1024 both AT and CS provide intermittent ferial, epactal, paschal cyclic, bissextile and ab anno Incarnatione data and the first two and last of these have been tabulated wherever they occur. After AD 1071 these data are frequently presented with their numbers either partially or fully written in Irish and, in these cases, the numbers have been converted to Roman numerals in order that they may be readily compared with the parallel AU series of these data, however the conversion has been indicated by placing it in brackets, e.g. at AD 1074 is given ‘Kl.[.iiii.f.l.x.ix.]’, representing AT’s Kl. Enair for cétain .ix. dec fuirti. Thus these square brackets only imply that the form has been altered, not the substance.

Regarding the practical matter of locating the full-text entry associated with any record token from AT, in Stokes’ edition from AD 488 forward the parallel AU entry may be used as an index since Stokes has listed cross references to the MS AD recorded in AU, and to the editorial AD presented in the published editions of other annals, immediately ahead of each kalend, see page 204 of ‘The Chronology’ for an example. Before AD 358, i.e. for fragments one and two of AT, Stokes has no such cross references, so the page numbers from the (Felinfach 1993) edition of his work have been suffixed in italic to the token of the first kalend on that page, see for example AD 354. To locate entries in Hennessy’s edition of CS the synchronised AD may be employed as an index using Hennessy’s marginal AD as an approximate guide. Finally, since a chronological feature of the primary MS for CS is O’Flaherty’s AD annotations, which Henessessy reproduced fully as footnotes to his edition, these have been recorded in the ‘Remarks’ column up until the CS lacuna beginning at AD 723, from which it will be seen that while generally they reconcile closely with the synchronised AD, on occasions they are erratic.

AC - Annals of Clonmacnoise

As this collection has preserved practically no chronological structure the best we may do here is to collate the tokens of its recorded records against the same records found in AT/CS. These are found to be in virtually identical sequence, and hence the synchronised AD provides a chronology for this collection; the very occasional re-sequencing in AC has been noted in the ‘Remarks’ column. To locate the full text of these tokens in Murphy’s edition of AC, the intermittent page references to records common to AT, CS and AC are given in italics following the ferial data up to AD 722. From AD 723 forward the AD interpolations which Murphy placed at the start of a line and followed by a period plus hyphen, e.g. Murphy p. 113 ‘722.-’, have been entered in italic opposite the appropriate kalend. These data ultimately derive from Ruaidhri O’Flaherty’s interpolations into the Armagh MS of the AC, and it will be seen that they are practically all inaccurate, some seriously so. Some of them are also misplaced amongst the body of records for a single year, e.g. Murphy’s ‘723.-’ should be located before rather than after the death of Colman Wamagh, and I have adjusted it accordingly. Unsatisfactory as they are for chronological purposes, Murphy’s interpolated ‘AD’ provide the only efficient means of indexing the only published edition of this important collection.

AU - Annals of Ulster

When we try to collate AU’s record events against those of AT/CS over the fifth and sixth centuries we repeatedly find that they occur either under different years or in a different sequence within a year. In these circumstances it is quite impossible over these centuries to collate AU’s record tokens in parallel with those of AT/CS. Fortunately Mac Airt and Mac Niocaill in their excellent edition of AU have numbered the records appearing within each year, and, since each year in AU is given an Annunciation AD running strictly serially from AU 431 to AU 1012, we may refer to each record uniquely by means of these numbers. For example, AU 432.1 refers to the record Patricius peruenit ad Hiberniam. Note it is essential that the MS Annunciation AD be used, because the marginal AD notation supplied by Mac Niocaill does not run serially, since it omits the number ‘488’ on page 55. By using these MS AD in this way as numerical record tokens, we may both refer uniquely to each event in AU and indicate simultaneously precisely its location in AU’s chronological structure. Furthermore we may re-position these tokens so that they align with the corresponding token in AT/CS. This is effective because many of the records found in AU up to the tenth century are also found in AT/CS and, in these circumstances, there is no need to reproduce the textual version of the record token since it already appears under one of AT, CS or AC. Of course, in the event that the record is unique to AU, we reproduce both the numeric and the textual record token. In this way we are able to show simultaneously, for all AU records, their chronological position in AU and their chronological relationship to that of AT/CS.

AU’s own chronological apparatus found in the prima manu of TCD MS 1282 consists of the words Kl. Ian [or Ien] Anno Domini followed by the Annunciation AD year in Roman numerals; for example, the record of Patricius peruenit is preceded by:

Kl Ien. Anno Domini .ccccº.xxxº.iiº.

Because in the range of years AU 431-663 fairly long sequences of AU’s events are found to be closely parallel to those found in AT/CS it was decided to tabulate AU’s chronological tokens in full so as to explicitly display the chronological relationship between AT/CS and AU. This is initiated with AU 431 aligned with AD 431 and the alignment remains thus until AU 574 when AU commences its own restoration of the missing kalends. In this interval AD 431-573 it must be emphasised that, although the AU years appear to be synchronised with the AD years, because they are Annunciation years they are actually high by one year. For example, AU places Patricius peruenit at Anno Domini .ccccº.xxxº.iiº., which when converted to a Circumcision AD changing on 1 January, equals AD 433. AT/CS and AU finally reach proper synchronism at AD 660. Between AD 493 and AD 536 the chronological relationship between AT/CS and AU exhibits repeated shifts and is significantly disturbed, as has been fully discussed in pp. 232-6 of ‘The Chronology’. Between AD 573, where AU restores its first kalend, and AD 659 where we have restored the last kalend to AT/CS, the numerical relationship between the two chronologies changes at each kalend restoration. Thereafter the synchronism established between AT/CS and AU at AD 660 is sustained at least until AT ends at AD 1178, excepting of course during AT’s lacunae, and until CS ends at AD 1150 excepting again its lacunae and omitted kalends at AD 905, 960, 1064 and 1080. Because of the stability of this chronological relationship between AT/CS and AU the latter’s kalends have been omitted from AD 741 onwards, excepting the interval AD 767-803 where lacunae in both AT and CS mean that we must rely on AU’s kalends and ab anno Incarnatione data. However the presence at AD 773 and 788 of accurate eclipse records in AU, together with its integrity with CS when it resumes in AD 804, provide good grounds to trust the chronology of AU over the interval AD 767-803.

If the order of the AU tokens within each year is examined, starting from the middle of the sixth century, it will be seen that they regularly appear in counting sequence, viz. 1, 2, 3, …, showing that records that AU has in common with AT/CS/AC occur in identical order in all these collections. This correspondence is in fact first noticeable as soon as the disturbed chronology of AU over AD 493-536 ends. For example, at AD 569 AT/CS have four records in common with AU, viz 1) Iug. Fergus, 2) Aennu q., 3) Ite q., 4) Gillas [q.], which occur in this identical order in AU 569.1-3. It is evident that this correspondence in the ordering of their common records is the result of their having drawn from a common source, and the correspondence is strongly sustained until the early tenth century, but is discernible up until AT ends. For example at AD 752 AT and AU have eleven records in common, all ordered identically, at AD 870 CS/AC and AU have five records in common, all ordered identically, and at AD 1173 AT and AU have three records in common, all ordered identically. In these circumstances the years at which this ordered relationship breaks down become of interest, and I here note two of these:



At AD 573 AU restores its first kalend, together with a unique record of the meeting at Droma Ceat, cf. ‘The Chronology’ p. 231, and its records for the subsequent year AD 574 are in complete disorder, viz. AU 575.4,2,1+3. It appears then that the interpolation of this kalend briefly disrupted the compiler’s systematic copying of entries in the order of their occurrence in the exemplar.


At AD 913 the four records in common with CS/AC appear in AU as AU 912.2,6,4,1, and following this year the textual and semantic relationship of entries in common between AT/CS/AC and AU become much more complex, viz. substantial differences, including contradictions, regularly occur. It is clear then that AD 913 marks a major change in the modus operandi of the compiler of AU.

AI - Annals of Inishfallen

The considerations when collating the records of AI are very similar to those of AU inasmuch as, up to at least the seventh century, it contains very few items not already found in AT/CS. Thus numerical record tokens, analogous to those described for AU and derived from Mac Airt’s edition, have been used; however, the following points should be borne in mind. Up to and including the arrival of Patrick, Mac Airt used the serial numbers §1-391 to uniquely label all the pre-Patrician records, so for these records I have used these numbers prefixed by the tag ‘I§’ to identify AI’s records. In the case where there is more than one record at a serial number, then these are distinguished serially by the extensions ‘.1’, ‘.2’ etcetera; where there is only one record this extension is omitted for the sake of compactness. For example, Jerome’s death at AD 417 is identified simply as I§340, whereas the synchronism at AD 432 on the death of Connculaind is identified as I§389.5, being the fifth record at I§389. After Patrick’s arrival Mac Airt endeavoured to supply an AD chronology in the margin of his edition based on that of AU, but faced great difficulties due to the level of chronological corruption inherent in AI. However, as these are the only practical means of indexing the post-Patrician events in his edition they have been used, analogously, with ‘I:’ prefixed. Thus at AD 456 the token I:453.1 refers to the entry Marciani mors qui regnauit annis .uii., which appears in Mac Airt’s edition against his marginal ‘A.D.’ of 453. It should be noted that in his endeavour to follow AU's chronology Mac Airt has freely both interpolated and omitted kalends, as the following table, complete up until AI 766, illustrates:

Mac Airt’s AD



AI 473-480

6 kalends


AI 482-485

2 kalends


AI 489-491

1 kalend


AI 509-511

1 kalend


AI 519-521

1 kalend


AI 560A-B


2 kalends

AI 649-652

2 kalends


AI 667-669

1 kalend


AI 711-713

1 kalend


AI 744-747

2 kalends


AI 747a


1 kalend


17 kalends

3 kalends

This gives a good impression as to the level of chronological corruption inherent in AI and shows very clearly that Mac Airt’s marginal ‘A.D.’ cannot be regarded as an accurate serial count of the kalends in the MS.

Given this degree of chronological corruption there is nothing to be gained by tabulating the kalends structure of AI against that of AT/CS and, accordingly, it has all been omitted with exception of a few kalends between AD 433-454 which preserve a mixture of ferial and lunar data. These chronological tokens from AI have been aligned with the corresponding token from AT/CS and prefixed with their location in Mac Airt’s edition; for example, 'I:440 K.ii.f.xii.l.' is a kalend with ferial .ii. and luna .xii. found at AI 440 and is synchronous with AT/CS at AD 440.

Annals of Boyle and Roscrea, the Dublin fragment and the Fragmentary Annals

Collation of all the remaining annal collections has been done along the lines described above for AI; that is, the serial numbers used in their published editions have been used with a single letter tag prefixed to the serial number to indicate the source from which it comes. Of these additional collections the only one to preserve chronological apparatus worth collating is AR, which, between the years AD 444-7, 571-7, 583-8 and 596-601, preserves marginal ferial data which are clearly cognate with the ferial data of AT/CS. These data have been collated in a style analogous to that of AI described above.

Bede's Chronicon Maiora

As discussed in detail in 'The Status' pp. 116-130 there are good reasons to believe that the pre-Patrician sections of AT and AI and Bede's Chronicon maiora (CM) all derive from a common source, identified as a chronicle compiled by Rufinus in the early fifth century. The structure and content of this source is best preserved in AT and AI, and in order to show explicitly the relationship between AT, AI and CM, all the entries found in common have been recorded by using the serial numbers of Jones' edition of CM, prefixed by the tag 'C:'


The complete list of tags and the edition with which the serial number is associated is as follows:


Annals of ... - Acronym




Inishfallen - AI

Mac Airt

I:434.1 at AD 434


Boyle - AB


B:146.1 at AD 440


Roscrea - AR

Gleeson & Mac Airt

R:91 at AD 445


Dublin fragment - DF

Mac Airt & Mac Niocaill

D:197 at AD 378


Fragmentary - FA


F:22 at AD 663


Bede - CM


C:545 at AD 643

The edition references are:

Mac Airt, S. The Annals of Inisfallen (Dublin 1951).

Freeman, A.M. ‘The Annals in Cotton MS Titus A xxv’ in Revue Celtique 41 301-30, 42 283-305, 43 358-84, 44 336-61, (1924-27).

Gleeson, D. & Mac Airt, S. "The Annals of Roscrea", Proc. Royal Irish Academy 59 C (1958)138-80.

Mac Airt, S. & Mac Niocaill, G. The Annals of Ulster to A.D. 1131, (Dublin 1983).

Radner, J.V. Fragmentary Annals of Ireland (Dublin 1978).

Jones, C.W. Bedae Venerabilis Opera, CCSL CXXIII B (Turnholt 1977).

Presentation and Status of the Collation

The collation has been implemented as a series of tables in Word 6.0 which are designed to print on an A4 page in landscape orientation so as to provide the maximum width for parallel tabulation. Time is considered to advance down the page and all the tokens placed on one line are taken to refer to the same event. As no horizontal lines are printed it is recommended that a ruler be used to ensure correct alignment for tokens widely separated across the table. For years when all the annal sources are available these are presented by columns as follows:






Synchronised AD year


Julian ferial for the AD year


AT event tokens


CS event tokens


AC event tokens


AU event tokens


AI, AB, AR, DF, FA, CM event tokens



In order not to have large areas of blank space between the event tokens when there are lacunae in any of the sources AT, CS, AC and AU, the collation has been split into a series of sub-tables based on these lacunae as follows:


AD Interval

Collates ...























The collations for these intervals have been further subdivided in order to obtain Word and HTML files averaging about 70K bytes in size, in order to facilitate their downloading across the Internet and their maintenance. At the present time (19 September 2000) the following are the extent and level of the collation of each source:



AD Range

Collation includes -



All chronological and record entries



All chronological and at least one record entry per annum



All chronological and record entries



All chronological and at least one record entry per annum



All record entries



At least one record entry per annum



All chronological and record entries



At least one record entry per annum



Largely only record entries found also in AT/CS



All record entries



All record entries



All record entries



All record entries



All record entries found in the annals

The present collation therefore covers from the beginning of the Christian era up to the end of both AT and CS and it is substantially comprehensive up until AD 766, and this coverage serves two purposes -


It establishes a synchronized chronology for all these annals from the beginning of the Christian era up to AD 1178


It displays substantial detail regarding the structure and content of the Iona chronicle, which is considered to extend up to c. AD 740, and for the first 26 years after its removal to Ireland, allowing identification of its important features.

Applications of the Collation

The principle application for which the collation has been designed is to provide synchronised AD dating for all the events recorded in the annals. For events occurring up to AD 766 this involves simply locating the record token of the event in the collation and reading off the AD from the left-hand column. After AD 766, for records which have been collated, this same procedure should of course be followed, however there is a substantial chance that the record of interest has not been collated and so no token for it appears in the collation. In this case the remaining records in the same year must be examined until one is found whose token does appear in the collation. For example the entry Illulbh, Rí Alban moritur appears in CS under Hennessy’s marginal ‘960’ but does not appear in the collation. However a token of the immediately preceding record, viz. Crech la Flaithbertach does appear in the collation at AD 962 and this therefore is the synchronised date to be assigned to Illulbh’s death.

An application complementary to synchronising their AD is to provide efficient identification of parallel records of all events entered in the annals, and this may be done comprehensively up to AD 766. Thus someone interested in the death of Baethéne, Columba’s successor as abbot of Iona, may establish at a glance that the synchronised date is AD 596 and that parallel entries occur in AT, CS, AC, AU, AR, AB, FA and the full text of all these entries may then be easily located and collated. It is to be hoped that this will facilitate the use of the annals for historical studies, which have hitherto been greatly impeded by the uncertainty attached to the dates inserted in the various published editions. For example, Mac Airt and Mac Niocaill’s edition of AU places Baethéne’s death at 598, Mac Airt’s edition of AI places it at 601, Murphy’s edition of AC offers no date, the published editions of AB and AR cite ‘AU 598’ which is AU’s MS Anno Domini incremented by one year, and finally Stoke’s edition of AT cites AU’s MS year as ‘AU.597’. As can be seen these published editions provide three different AD dates, all of which differ from the synchronised AD.

A further application of this collation over the interval AD 1-766 is to use it to identify records of events unique to each source, since the token for such an event must stand on its own in a line. In this way it is straightforward, for example, to observe that AT presents a sequence of records which are also found in Bede’s Chronicon Maiora, at AD 492 (Trasamundus), 502 (Simacus P.), 526 (Iohannes) and 526 (Iustinus), to cite just a few of these. Similarly between AD 367-431 AI preserves, mostly uniquely, a sequence of extracts also found in Prosper’s chronicle. These unique records are important clues to the text history of the annal collection preserving them. Even after AD 766 where the record collation is partial, a good idea of the content relationship of the different annals may be obtained by examining the years for which a complete collation has been done, generally at decadal years; for example at AD 780 we see that AC has five entries in common with AU and they are in identical order, evidently reflecting their common source. Again, if AT/CS/AU are examined over the range AD 974-1023 it will be seen that they transmit numerous records in common, many of which are both semantically and textually closely related. Furthermore it will also be noted both that the first entry in AU is normally also found in AT/CS, and that sequences of mutually common records still are often presented in close or identical sequence in all three annals, see AD 1022 for example. Such widespread correspondences clearly point to a common source still underlying all three annals at this date. Hence the conclusion presented by Kathleen Hughes in Early Christian Ireland: Introduction to the Sources (London 1972) p.107, viz., ‘To sum up, AU and Tig.. represent a Chronicle of Ireland which must have been drawn up some time before 913, for at this point the two families diverge. A copy was made then and was subsequently taken to Clonmacnoise, where additions were inserted’, is unsustainable. In ‘The Status’, Peritia 12(1998) p.111, n.35 I pointed out that Hughes’ definition of her ‘Chronicle of Ireland’ is unsatisfactory.

A further application of the collation is to use it to observe closely what material is in common and what is omitted between cognate annals. For example at AD 588, relative to both AT and AC, CS has omitted the battles of Leithrigh and Muighe and the obiit of Lughdach, so we may explore this to see whether a particular political outlook is implied by these omissions. Similarly at AD 622 CS omits the death of Ailella and the battle of Lindais from a long set of entries found otherwise fully in AT and AU. Historical evaluation of these omissions should sharpen considerably our knowledge of the editorial policy employed when CS was compiled. Similar methods may be applied to the smaller collections to identify what factors have influenced their compilation and hence to clarify their inter-relationships.


This article has set forth the rationale and the methods used to construct the following collation of the various annals over the years AD 1-1178. This has been done, piecemeal, by the author and, while as much care as possible has been taken, given the sheer volume and complexity of the material it is virtually certain that it contains some omissions, mis-locations and mis-identifications. It will be greatly appreciated if these would be notified to him upon discovery, in order that the accuracy and the value of the collation may be enhanced. These may be emailed to him at or posted to D.P. Mc Carthy, Department of Computer Science, Trinity College, Dublin 2, Ireland.