The cause of the battle was the pretension of the petty Prince of Ulidia, which comprised little more than the present county of Down, to be recognised as Prince of all Ulster. Now the Hy-Nial family, not only had long given monarchs to all Ireland, but had also the lion's share of their own Province, and King Donald as their head could not permit their ascendency to be disputed. The ancestors of the present pretender, Congal, surnamed "the squint-eyed," had twice received and cherished the licentious Bards when under the ban of Tara, and his popularity with that still powerful order was one prop of his ambition. It is pretty clear also that the last rally of Druidism against Christianity took place behind his banner, on the plain of Moira. It was the year 637, and preparations had long gone on on both sides for a final trial of strength. Congal had recruited numerous bands of Saxons, Britons, Picts and Argyle Scots, who poured into the harbours of Down for months, and were marshalled on the banks of the Lagan, to sustain his cause. The Poets of succeeding ages have dwelt much in detail on the occurrences of this memorable day. It was what might strictly be called a pitched battle, time and place being fixed by mutual agreement. King Donald was accompanied by his Bard, who described to him, as they came in sight, the several standards of Congal's host, and who served under them. Conspicuous above all, the ancient banner of the Red Branch Knights-"a yellow lion wrought on green satin"—floated over Congal's host. On the other side the monarch commanded in person, accompanied by his kinsmen, the sons of Hugh III. The red hand of Tirowen, the cross of Tirconnell, the eagle and lion of Innishowen, the axes of Fanad, were in his ranks, ranged closely round his own standard. The cause of the Constitution and the Church prevailed, and Druidism mourned its last hope extinguished on the plains of Moira, in the death of Congal, and the defeat of his vast army. King Donald returned in triumph to celebrate his victory at Emania and to receive the benediction of the Church at Armagh.