St. Columba, we are told by his biographer, warned the king of Dál Riada to refrain from making war in Ireland on the king of Ireland, and foretold that, if this warning were disregarded, disaster would befall the line of Aedán. Adamnanus goes on to say that this prophecy was fulfilled many years after St. Columba's death. This was written by Adamnanus about fifty years after the event to which he alludes, which was therefore within the memory of many who read his words. Domhnall Breac, king of Dál Riada, he relates, invaded the realm of the king of Ireland. And now, he says, the fulfilment of the warning is visible in the miserable condition to which the kings of Dál Riada are reduced, humiliated by their triumphant enemies. He refers to the events connected with the battle of Moira in 637. The king of Ireland at the time was Domhnall son of Aedh, that is, son of the king who presided over the Assembly of Druim Ceata. Taking advantage of a quarrel between the Irish monarch and a prince of the north-eastern Picts of Ireland, the Scottish king, as we may call him, put himself at the head of a combination of the north-eastern province and took the field in Ireland. The battle between the two Domhnalls took place at Moira, near Lisburn, and the king of Ireland was victorious. Here we have an instance of the method of contemporary Irish chroniclers. To the chronicler's mind, everybody knew everything that was to be known about this battle and its circumstances, and his record of the event is a mere memorandum in two words. But what were the disastrous results, which, on the testimony of Adamnanus, were notorious when he wrote, _i.e._ about the year 690? The Irish kingdom in Scotland seems as strong as ever, and is on the eve of a great increase of its power and territory. Once more, as in the instance of the judgment of Druim Ceata, the reference must be particularly to the old Irish kingdom of Dál Riada, which drops into obscurity in the Irish records about that time, possibly becoming tributary either to the neighbouring Picts or to the Northern Ui Néill, whose territory had then extended to the banks of the Bann.