There are two factors that make for the completeness and permanence of conquest--namely, physical superiority and moral superiority. In the art of war and in the apparatus of centralised government, the invaders, we have seen, were superior to the Irish. They could even use the Church as an instrument of the State, and Mr. Orpen boasts that, whereas the Irish bishop of Dublin, Lorcán O'Tuathail, was only a saint, the English bishops who succeeded him were statesmen. Warfare by incastellation, carried on for seventy years, brought three-fourths of the country under control. If to this physical superiority we must add the moral superiority claimed for the Feudal _régime_ by modern admirers--if not by its contemporary champion in letters, Giraldus--there is left only one possible explanation of the failure, the perversity of the Irish mind, afflicted with a double dose of original sin, refusing to recognise either physical superiority in the arts of war or moral superiority in the arts of peace. Another factor must not be forgotten. The second generation of Feudalism in Ireland was in full possession of all the military resources of the greater part of the country. Just as, in the beginning of the invasion, they had led armies of conquered Flemings and conquered Welshmen, and as a few years later they led a force of conquered Norsemen from Dublin to the battle of Thurles, where they were defeated by Domhnall O'Briain, so in their later wars they led armies of conquered Irishmen for the completion of the conquest. And even conquered Irishmen were not bad fighting material. Two causes have been assigned by modern writers for the failure of the conquest. One cause alleged is the invasion by Edward Bruce in the years 1315 to 1318. In view of the fact that Bruce's undertaking was itself an ignominious failure, another cause assigned is the transference of the Feudal lordship of Connacht and Ulster from the De Burghs, resident in Ireland, to the Plantagenets, who were absentees. This happened after 1333.