During the whole of St. Patrick’s mission his invariable plan was to address himself in the first instance to the kings and chiefs. He understood the habits of the Irish people; and he well knew that if the chief became a Christian, the people, with their devotion for their hereditary rulers, would soon follow. He now resolved to go straightway to Tara, where king Laeghaire and his nobles happened at this time to be celebrating a festival of some kind. Bidding farewell to his friend Dicho, he sailed southwards to the mouth of the Boyne, where leaving his boat, he set out on foot with his companions [145] across the country for Tara, and arrived at Slane on Saturday, Easter eve, a.d. 400. Here he prepared to celebrate the Easter festival, and towards nightfall - as was then the custom - lighted the Paschal fire on the hill of Slane.

 At this very time it happened that the king’s people were about to light the festival fire at Tara, which was a part of their ceremonial; and there was a law that while this fire was burning no other should be kindled in the country all round, on pain of death. The king and his courtiers were much astonished when they saw the fire ablaze upon the hill of Slane, nine miles off’; and when the monarch inquired about it, his druids said:- ‘If that fire which we see be not extinguished to-night it will never be extinguished, but will overtop all our fires: and he that has kindled it will overturn thy kingdom.’ Whereupon the king, in great wrath, instantly set out in his chariot with a small retinue; and having arrived near Slane he summoned the strangers to his presence. He had commanded that none should rise up to show them respect; but when they presented themselves one of the courtiers, Ere the son of Dego, struck with the saint’s commanding appearance, rose from his seat and saluted him. This Ere was converted and became afterwards bishop of Slane; and to this day he is commemorated in the name of a little chapel beside the Boyne at Slane, called St. Erc’s hermitage. The result of this interview was what St. Patrick most earnestly desired; he was commanded to appear next day at Tara and give an account of his proceedings before the assembled court.

 The next day was Easter Sunday. Patrick and his companions set out for the palace, and on their way they chanted a hymn in the native tongue - an invocation for protection against the dangers and treachery by which they were beset; for they had heard that persons were lying in wait to slay them. This hymn, which is called Faed Fiada, or the Deer’s cry, from the legend that Patrick and his companions appeared in the shape of deer to the intended assassins, was long held in great veneration by the [146] people of this country, and we still possess copies of it in a very old dialect of the Irish language. [1]

In the history of the spread of Christianity it would be perhaps difficult to find a more singular and impressive scene than was presented at the court of king Laeghaire on that memorable Easter morning. The saint was robed in white, as were also his companions; he wore his mitre, and carried his crozier - the Bachall Isa or staff of Jesus - in his hand; and when he presented himself before the assembly, Dubhthach [Duffa] the chief poet rose to welcome him, contrary to the express commands of the king. In presence of the monarch and his nobles, the saint explained the leading points of the Christian doctrine, and silenced the king’s druids in argument.

The proceedings of this auspicious day were a type of St. Patrick’s future career. Dubhthach became a convert, and thenceforward devoted his poetical talents to the service of God; and Laeghaire gave permission to the strange missionaries to preach their doctrines throughout his dominions. The king himself was almost moved to become a Christian, but there is good reason to believe that he died an obstinate pagan. Patrick next proceeded to Tailltenn (pp.89, 90), where during the celebration of the national games he preached for a week to the assembled multitudes, making many converts, among whom was Conall Gulban, brother to king Laeghaire.

 We find him soon after, with that intrepidity and decision of character for which he was so remarkably distinguished, making straight for Moy Slecht, where stood the great national idol Crom Cruach, surrounded by twelve lesser idols (p.141). These he destroyed, and thus terminated for ever the abominations enacted for so many ages at that ancient haunt of gloomy superstition.

[...]

Note
It is printed with translation (by John O'Donovan) in Petrie’s Tara; and also in Stokes’s Tripartite Life of St. Patrick.