Cummian’s Paschal letter of c. AD 632 provides a unique account of a Christian community changing their Paschal tradition. However, while scholars have disagreed upon the tradition adopted by Cummian’s community most have accepted that it related in some way to the 532-year Paschal table compiled by Victorius of Aquitaine in AD 457, but they have been unable to explain the relationship. This article identifies that all the published editions of Victorius’s table preserve substantial redactions transmitted by the manuscripts of the table. When these redactions are corrected Cummian’s account of the table that saint Patrick ‘brought and made’, always observing Paschal luna 14 after 21 March, corresponds to Victorius’s tabulated Paschal criteria when the saltus of each 19-year cycle is retarded by thirteen years. It thus emerges that in c. AD 458 Patrick brought to Ireland a 532-year table that he had adapted so that its Paschal dates and lunae were identical with those of the Alexandrian Paschal table compiled by Annianus in c. AD 412. This was the Alexandrian table endorsed by Cyril, bishop of Alexandria in AD 418, excerpts of which were transmitted subsequently by the Prologus S. Cyrilli of c. AD 456, Dionysius Exiguus in AD 525, Isidore in c. AD 636, and Bede in AD 725. Consequently, in Ireland the disciples of Patrick since c. AD 458, and the southern Irish churches that adopted the decision of Mag Léne in c. AD 632, were celebrating the Paschal criteria that would be declared as canonical for the Roman church by pope Honorius (AD 625–638). Subsequently, in AD 716, Iona and its familia adopted these same Paschal criteria as transmitted by the continuation of Dionysius’s Paschal table. Daniel Mc Carthy, 'The Alexandrian Paschal Table Brought to Ireland by Saint Patrick, c. AD 458', Peritia, 35 (Turnhout: Brepols, 2024), 75–122

The structure and termini of the 84-year Paschal table with a 14-year saltus followed by the early mediaeval churches of Britain and Ireland remained a matter of conjecture until 1985, when Daibhi O Croinin identified a full copy of the table in MS Padua, Biblioteca Antoniana, I.27. This paper undertakes a detailed analysis of the Padua table and demonstrates that its achievement of Anatolius' Paschal termini of luna 14-20 between 26 March and 23 April resulted from Sulpicius Severus' skilful exploitation of the synchronism between his 14-year saltus and the 28-year solar cycle.

Substantial annalistic chronicles of Irish affairs exist in a number of medieval versions, but they exhibit considerable variation both in the sequences of events and the chronological apparatus used to link each year to the Julian calendar. Of these, the Anno Domini years of the Annals of Ulster have been principally relied upon by historians. However, these are demonstrably incorrect from the seventh to the eleventh centuries. Moreover, its remaining chronological data of ferials and lunar epacts at the kalends of January, that is, the day of the week and the age of the moon on 1 January, are almost all interpolations by a later scribe. On the other hand, the Annals of Tigernach and the Chronicum Scotorum have only kalends and ferials marking the commencement of each year from the Incarnation up until the mid-seventh century. Because these kalends and ferials are susceptible to scribal miscopying they were dismissed by historians and textual scholars as "hopelessly confused". However, analysis of the 28 year cycle of the ferials reveals that they possess a powerful error-correction property. Exploitation of this property has enabled the restoration of all the missing kalends and erroneous ferials of the Annals of Tigernach and Chronicum Scotorum, as well as of the closely related Annals of Roscrea, known collectively as the Clonmacnoise group. Using computer table structures, the kalends and ferials and events of these three have been synchronized with the Anno Domini years over the range AD 1-1178, and this tabulation, with cross-references to the other Irish medieval annals, has been made available online at www.irish-annals.cs.tcd.ie. In this chapter the process of analysis, correction, and synchronization is illustrated, taking the year of the death of St Patrick as an example.

The view of Mac Airt and Mac Niocaill in their 1983 edition of AU that the annals of f 12–14 of TCD 1282 are indeed part of the Annals of Ulster has recently been vindicated. Analysis of the chronological apparatus of f 12–14 reveals that their author was responsible for the introduction of Dionysiac epacts and continuous Anno Domini into the Irish annals. He accomplished this by an extraordinary series of interpolations into the pre-Palladian section of the Iona Chronicle that he used as source, demonstrating both his computistical skill and profound indifference to historical chronology. By ad 431 his apparatus was accurately synchronised with all the Dionysiac chronological criteria, and he continued with it, re-ordering many events through the fifth and sixth centuries. In the seventh century he omitted a single kalend, which put all his subsequent apparatus in arrears by one year. Collation of AU with the other annals indicates that his compilation continued to c.1019 and was completed shortly after 1022. This compilation is identified with AU’s ‘Liber Cuanach’, and Cuan hua Lothcháin (†1024) is proposed as the author.

Chronological divergence between the different early Irish annals has hampered the use of their many unique records of events in Ireland, Britain and the European continent as historical sources. This paper reviews recent work which has demonstrated that their original chronological apparatus consisted of a kalend (Kł) followed, until at least the mid‐seventh century, by the ferial of 1 January, and from this a consistent chronology has been restored for the annals over the years AD 1–722. In addition, critical examination of their regnal and episcopal successions has established that the ‘world history’ section of these annals and Bede’s Chronica maiora are not mutually dependent, but rather share a common source which has been identified as a kalend‐plus‐ferial chronicle composed by Rufinus of Aquileia in the early fifth century.

This is a critical chronological and textual analysis of all annalistic entries on the life of St Brigit of Kildare. It emerges that AT and CS have best preserved the chronology originally given Brigit in the Iona chronicle which placed her death at ad 524, aged 86 years. AU and AI transmit a later tradition, subsequently interpolated into the Iona chronicle, that she died aged 70. It is argued that the author of the original Iona chronicle entries was St Columba, a competent computist and near-contemporary of Brigit. Hence his chronology is trustworthy. To check this, a chronological evaluation of the earliest surviving Vitae S. Brigitae reveals that the chronology of all the individuals found jointly in the Vita I and the annals is consistent, implying that both sources have transmitted a chronology which is essentially correct, a result which supports the historical priority of Vita I over Vita II. Finally, examination of the context of Cogitosus’s date for Brigit’s death shows that he aligned it to correspond with existing non-christian celebrations already held in Kildare.

This investigation of the pre-Patrician material in Irish annals first reviews the historiography, then examines the chronology of Roman imperial successions, and reveals a conflation of Eutropius's Breviarium with Jerome's Chronicle. Collation with Bede's Chronicon maior shows these annals and Bede have a common source. The annals preserve more of this source and its chronological apparatus. The Alexandrian episcopal succession in AT derives directly from Rufinus's History, and the errors suggest that he himself constructed it. The Hebrew succession in Bede and AI reveals divergences from Jerome's chronology, not plausibly the work of Bede but appropriate to Rufinus. Hence the hypothesis that Rufinus compiled a chronicle in the early fifth century, that it came to Ireland with the 84-year paschal table of Sulpicius Severus, and that it was used in Iona in the mid-sixth century as the basis for the Iona Chronicle.