He came to rule for his own benefit, or for the benefit of his nation.

The worst of kings has, at least, an hereditary interest in the country which he governs; the best of lord deputies might say that, if he did not oppress and plunder for himself, other men would do it for themselves: why, then, should he be the loser, when the people would not be gainers by his loss?
When parliaments began to be held, and when laws were enacted, every possible arrangement was made to keep the two nations at variance, and to intensify the hostility which already existed.

The clergy were set at variance.

Irish priests were forbidden to enter certain monasteries, which were reserved for the use of their English brethren; Irish ecclesiastics were refused admission to certain Church properties in Ireland, that English ecclesiastics might have the benefit of them.
Lionel, Duke of Clarence, when Viceroy of Ireland, issued a proclamation, forbidding the "Irish by birth" even to come near his army, until he found that he could not do without soldiers, even should they have the misfortune to be Irish.

The Irish and English were forbidden to intermarry several centuries before the same bar was placed against the union of Catholics and Protestants.