According to the law of Tanistry, the succession fell to his cousin Eogan, son of that Gabran who had been defeated and slain by King Brude in 560; and Columba would have preferred to see him succeed, as he regarded him with affection; but he probably thought that his brother Aidan would suit his purpose better. Aidan was connected through his mother with the Britons of Strathclyde, and had played his part for a few years in the British wars. Columba announced that he had seen, ‘on a certain night, in a mental ecstasy, an angel sent to him from heaven, and holding in his hand a book of glass, containing the appointment of kings; and having received the book from the hand of the angel, had read therein the name of Aidan; and on his being reluctant to appoint him king, the angel had struck the saint with a scourge,’ and added these words,—‘Know for certain that by God am I sent to thee with the book of glass, that in accordance with the words thou hast read therein, thou mayest inaugurate Aidan into the kingdom.’ This was repeated three times. [Sidenote: A.D. 574. St. Columba inaugurates King Aidan and attends the assembly of Drumceatt.] There was no gainsaying such a statement by one in Columba’s position. Aidan came to Iona, and Columba there ordained him king. During the words of consecration, he prophesied that the throne would remain to his children, grandchildren, and great-grandchildren, and, laying his hand upon his head, he consecrated and blessed him.[246] Columba’s object in inaugurating Aidan with this solemn rite was to place him in the rank of an independent king, and to induce the Pictish monarch to recognise him as such over the whole of the Dalriadic territories. In order to secure the former object, he took advantage of an approaching synod, summoned to meet at Drumceatt, a mound on the river Roe, in the county of Londonderry. This great convention was called together by Aedh, son of Ainmire, king of Ireland, in the year 575,[247] and consisted of all the petty kings and heads of tribes, and of the principal clergy of Ireland. Columba attended it, accompanied by King Aidan, and by a retinue who are thus described by the poet Dallan Forgaill:— Forty priests was their number, Twenty bishops, noble, worthy, For singing psalms, a practice without blame, Fifty deacons, thirty students.[248] The assembly was held not far from Columba’s monastery of Derry; and no doubt this retinue would consist of persons taken from his Irish monasteries, as well as of those who accompanied him from Iona. Columba’s object would be to make as imposing an appearance as possible; and there is no improbability in its having been composed not only of priests but of bishops.