For the wealth of knowledge which we have available to us today, about the past in Ireland we have to thank the various Annalists who dedicated their lives to compiling historical records based on their own personal experiences and those of their peers, as well as information which came to them via previous Annalists.

The annals were usually written in a matter of fact way, recording the date and the event without embellishment. The Annalists were in most cases monks working in teams, as is the case in the Annals of the Four Masters written between 1632 and 1636 by four monks, three of whom were brothers, as far as I understand these Annals have been translated and published in four volumes and are available to buy.

It is unlikely that every single piece of information is absolutely correct, however it is possible to test the accuracy of many of the entries, for instance in the account of the Battle of Clontarf fought by Brian Baruo in 1014 the annals state that it was fought on Good Friday, the 23rd of April, 1014 and that it began at sunrise, when the tide was full in. DR Todd of Trinity College, Dublin asked the Rev Samuel Haughton to calculate the time of high water in Dublin bay on this date, Rev Haughton found that high water occurred at half past five in the morning. The various Irish annals record eclipses and comets, most of these when checked against other sources confirm the accuracy of the Irish records.

All the Irish Annals record a battle with the Danes near Killarney in 812 in which the Danes were soundly beaten, they retreated and returned home leaving behind a large number slain. This is borne out by the Book of Annals written by Eginhard who was tutor to the Emperor Charlemagne.

Read about the various Irish Annals from Patrick Weston Joyce's A Concise History of Ireland.