THE great lordships of the Welsh marches constituted a phenomenon not found elsewhere in the area subject to the kings of mediaeval England, and a comparison with the English palatinates and the great liberties of Norman Ireland reveals some very remarkable features. Many of the powers which the marchers exercised were no doubt taken over from the Welsh princes whom they displaced, but this does not in itself explain why they were able to retain such powers. In Ireland at the end of the twelfth century another Norman conquest produced another series of great liberties in which Norman lords displaced Celtic kings who had exercised the powers of independent rulers, but the lords of the liberties of Leinster, Meath or Ulster were subject to the control of the royal government at Dublin in the same way as the greater English liberties were subject to royal control, and never attained a degree of independence comparable with the position held by the marchers. The difference seems most easily explained as being due to the simple fact that the marcher position was in essentials established in the reign of Henry I, while the Norman conquest of Ireland occurred two generations later, at the time when Henry II was extending the control of the crown in so many directions.